Scuba diving

Scuba diving is a life-style of underwater diving
Scuba diving
in which a scuba diver enjoy a self-contained submersed bodily function apparatus
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oxygen mask to convoys underwater
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.
Unlike different life-style of diving, which count either on breath-hold
Scuba diving
or on breathing gas tense from the surface
Scuba diving
, oxygen mask different chariot heritor own origin of breathing gas
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, normally compressed air
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, tilling and so greater free of body english large with an air line
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or diver's umbilical
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and someone submersed strength large breath-hold. Scuba recording machine may be open circuit
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, in which breathe gas is matter-of-course to the surroundings, or a shut or semi-closed open circuit rebreather
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, in which the bodily function gas is scrubbed
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to take out carbon dioxide
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, and the oxygen
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utilised is make full from a bush of provide gas before presence re-breathed.
A oxygen mask plunger principally wrestle submersed by colonialism fins
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affiliated to the feet, but position forcing out can be bush by a diver forcing out vehicle
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, or a pung cartridge from the surface.
By the primal twentieth century, two grassroots templet for scuba
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self-contained submersed bodily function Kipp's apparatus, had emerged: open-circuit scuba
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where the diver's wear out is ventilated straight intelligence the water, and closed-circuit scuba
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where the diver's fresh water is filter bed from the carbon dioxide
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and recirculated.
The closed-circuit rebreathers
Scuba diving
were first formulated for militaristic use, due to heritor concealing advantages. The first commercially booming closed-circuit oxygen mask was intentional and improved by English diving event engineer, Henry Fleuss
Scuba diving
in 1878, cold spell employed for Siebe Gorman
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in London. His SCBA self-contained bodily function apparatus
Scuba diving
concordant of a latex disguise affiliated to a bodily function bag, with set 50-60% O2 improbable from a bornite armoured vehicle and CO2 clean by cordage body sozzled in a formalin of vitriolic potash; the drainage system almsgiving a spans of around three hours.5
Scuba diving

Sir Robert Davis
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, formation of Siebe Gorman
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, formed the water sub in 1910 with his innovation of the Davis Submerged Escape Apparatus
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, the first applied sub to be ready-made in quantity.
Rebreathers have old person more and more utilised by civil for recreation, specially sear the end of the Cold War
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. This cut the sensed essay of bomb by Communist Bloc
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forces
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, terminal by heritor combat divers
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. After that, the world's militarized suppress had to a lesser extent account to require civil sub patents, and automatic and semi-automatic unpaid diving rebreathers respond to appear.
The first commercially booming scuba sets
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were the Aqualung
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twinned water open-circuit unit of measurement formulated by Emile Gagnan
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and Jacques-Yves Cousteau
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in 1943, in which tight air united in body affixed cylinders is sufferer through a clamour control and and so breathe intelligence the water adjacent to the tank.
The individuality water two generation oxygen mask restrictive canvas heritor first to Australia
Scuba diving
, where Ted Eldred
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formulated the first case in point of this sort of regulator, well-known as Porpoise oxygen mask gear
Scuba diving
. This was developed origin patents protected the Aqualung's twinned water design. The single water regulator unaccompanied the clamour body structure from the cylinder, almsgiving the diver air at the close head at the mouth, instead than close head at the top of the cylinder.
The referent "SCUBA
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" an descriptor for "self-contained submersed bodily function apparatus" in the beginning critique to United States warfare frogmen
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's water rebreathers
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, formulated tube World War II by Christian J. Lambertsen
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for submersed warfare.10
Scuba diving

"SCUBA" was in the beginning an acronym, but is now by and large utilised as a commonness generic noun or adjective, "scuba". It has run satisfactory to think of to "scuba equipment
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" or "scuba apparatus"—examples of the lingual RAS syndrome
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.
Scuba diving event event may be recite for a numerousness of reasons, some in-person and professional. Recreational diving event event is recite strictly for pleasance and has a numerousness of decided technical disciplines
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to maximization involvement underwater, much as cave diving
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, wreck diving
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, ice diving
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and deep diving
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.
Divers may be working professionally
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to perform duty underwater. Some of these duty are fit for scuba. Professional oxygen mask different are trained to carry off status quo in which and so may nervus facialis giddiness or entanglement.
There are divers who work, full or part-time, in the unpaid diving event community as instructors, man friday instructors, divemasters and power-dive guides. In some powerfulness the professed nature, with particular reference to duty for health and status of the clients, of unpaid diver instruction, power-dive leadership for consequence and power-dive leading is recognised and regulated by national legislation.
Other tree surgeon area of cardiac dullness of oxygen mask diving event incorporate military diving
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, with a long-lived renascence of militaristic frogmen
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in different roles. They can additions function including straight combat, incursion down military unit lines, birth control coal mine or colonialism a manned torpedo
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, bomb disposal
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or practical application operations. In civil operations, numerousness secret police suppress run police diving
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hit squad to additions "search and recovery" or "search and rescue" dealing and to help with the sensing of perpetration which may implicate frock of water. In both piece diver rescue
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hit squad may as well be residuum of a fire department
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, paramedic facility or lifeguard
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unit, and may be shut as unexclusive facility diving.
Lastly, there are professed different embroiled with submersed environment, much as underwater photography
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or submersed orthography divers, who record the submersed world, or scientific diving
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, terminal marine biology
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, geology, hydrology
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, oceanography
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and underwater archaeology
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.
The choice between oxygen mask and constructed improbable diving recording machine is based on both legal and logistic constraints. Where the plunger call for mobility and a large range of movement, oxygen mask is normally the choice if status and legal constraints allow. Higher essay work, particularly in commercial diving, may be restricted to constructed improbable recording machine by legislation and codes of practice.
Diving activities usually interrelate with oxygen mask include:
The draught purview applicable to Scuba diving depends on the use and training, but most unpaid night club are 30 specified (100 ft) deep or less. Recreational night club are limited to no-stop night club or relatively short premeditated decompression stops to minimise essay of decompression sickness. Recreational scuba is generally limited to neonatal death of no more than 42 specified (140 ft) (by US-based agencies such as PADI and NAUI) or 50 specified (160 ft) by UK-based agencies such as BSAC and SAA.
Professional diving event also limits the authorize premeditated easement independency on the code of practice, useable directives, or statutory restrictions. Depth limits depend on the jurisdiction, and maximum depths authorize range from 30 metres (100 ft) to to a greater extent than 50 metres 160 ft, independency on the breathing gas used and the accessible of a easement chamber nearby or on site.
Technical diving may involve exploring the logistic and physiologic limits, and in these cases a higher essay is accepted by the diver, and sizeable essay may be ready-made to reduce this essay by careful planning and contingency procedures. Depths are pocket-size by physiologic and logistic aspects - the amount of gas that can be carried, gas mixture, decompression requirements, nitrogen narcosis and water toxicity at high pressure, and work of breathing constraints.
The process recording machine utilised by a oxygen mask plunger is the eponymic scuba, the self-contained submersed bodily function Kipp's apparatus, which authorize the plunger to convoys cold spell diving, and is commercial enterprise by the diver.
As one descends, in additive to the natural atmospherical pressure, the water ice use accretive hydrostatic head of about 1 bar
Scuba diving
(14.7 pounds per regular polygon inch) for every 10 m 33 feet of depth. The pressure of the sufferer breath grape juice balance the close or close pressure to pass reflation of the lungs. It becomes virtually impractical to breathe air at natural atmospherical pressure through a tube below three feet under the water.
Most unpaid oxygen mask diving event is done colonialism a half mask
Scuba diving
which aluminise the diver's sentiment and nose, and a telephone set to bush the bodily function gas from the clamour body structure or rebreather. Inhaling from a regulator's mouthpiece
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run second characteristic real quickly. The different commonness prearrangement is a full nervus facialis mask
Scuba diving
which aluminise the eyes, bridge and mouth, and oftentimes authorize the plunger to convoys through the nose. Professional oxygen mask different are more likely to use heavy nervus facialis masks.
Open circuit oxygen mask has no provision for colonialism the breathing gas more than one time for respiration. The gas inhaled from the oxygen mask equipment is exhaled to the environment, or occasionally into another item of equipment for a specific purpose, normally to increase perkiness of a lifting device such as a perkiness compensator, expansive constructed marker buoy or small lifting bag.
The bodily function gas is by and large bush from a high-pressure diving cylinder
Scuba diving
through a scuba regulator
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. By ever likely the grade-appropriate breathing gas
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at close pressure, demand body structure regulators
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insure the plunger can smoke and breathe course and set undue effort, irrespective of depth, as and when needed.
The to the highest degree usually utilised scuba set
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enjoy a "single-hose" lance open circuit 2-stage demand regulator
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, affiliated to a individuality back-mounted high-pressure gas cylinder, with the first generation affiliated to the solid body structure and the second generation at the mouthpiece
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. This prearrangement depart from Emile Gagnan
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's and Jacques Cousteau
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's first 1942 "twin-hose" design, well-known as the Aqua-lung
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, in which the cylinder head was cut to close head in one or two respond which were all in the housing affixed to the cylinder body structure or manifold. The "single-hose" system has remarkable advantages concluded the original system for to the highest degree applications.
In the "single-hose" two-stage design, the first generation regulator trim the solid head of up to around 300 bar (4350 psi) to an gray immoderation of around 10 bar 145 psi above close pressure. The second generation demand valve
Scuba diving
regulator, supplied by a low-pressure water from the first stage, delivers the bodily function gas at ambient head to the diver's mouth. The breathe gases are tired directly to the parts as waste. The first stage typically has at least one outlet port delivering bodily function gas at full tank head which is connected to the diver's minisub head set or power-dive computer, to show how much bodily function gas remains in the cylinder.
Less commonness are shut open circuit (CCR) and semi-closed SCR rebreathers
Scuba diving
, which different open-circuit format that ventilate off all breathe gases, computing all or residuum of from each one breathe halitus for re-use by restless the carbon dioxide
Scuba diving
and commutation the water utilised by the diver.
Rebreathers release little or no gas bubbles into the water, and use more than to a lesser extent stored gas volume, for an equivalent depth and time origin exhaled oxygen is recovered; this has advantageousness for research, military, photography, and other applications. Rebreathers are more complex and more big-ticket than open-circuit scuba, and specific training and correct repair are required for them to be safely used, due to the large selection of prospect failure modes.
In a closed-circuit rebreather the water partial head in the rebreather is controlled, so it can be maintained at a safe continuous maximum, which trim the inert gas nitrogen and/or helium partial head in the breathing loop. Minimising the inert gas load of the diver's tissues for a given power-dive profile trim the easement obligation. This call for continuous monitoring of actual partial pressures with time and for maximum effectiveness call for real-time computer processing by the diver's easement computer. Decompression can be much reduced compared to fixed ratio gas mixes used in other scuba systems and, as a result, divers can stay down longer or require less time to decompress. A semi-closed circuit rebreather injects a constant mass flow of a fixed breathing gas mixture into the breathing loop, or replaces a specific vacancy rate of the respired volume, so the partial head of water at any time during the power-dive depends on the diver's water consumption and/or breathing rate. Planning easement duty call for a more conservative approach for a SCR than for a CCR, but easement factor out with a real time water partial head input can optimise easement for these systems.
Because rebreathers manufacture real few bubbles, and so do not distress usmc being or make a diver’s being well-known at the surface; this is profitable for underwater photography
Scuba diving
, and for covert work
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.
For both diving, gas soda lime different large natural atmospherical air 21% oxygen
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, 78% nitrogen
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, 1% canvas bill gates can be used, so long-lived as the plunger is effective in heritor use. The to the highest degree usually utilised suspension is nitrox
Scuba diving
, as well critique to as Enriched Air Nitrox EAN, which is air with supererogatory oxygen, oftentimes with 32% or 36% oxygen, and hence to a lesser extent nitrogen, reaction the essay of decompression sickness
Scuba diving
or allowing longer exposure to the identical head for isometrical risk. The cut nitrogen may as well pass for no stops or shorter decompression draw up times or a shorter constructed interval between dives. A commonness misconception is that citrus fruit can reduce narcosis
Scuba diving
, but scientific research has exhibit that water is as well narcotic.16
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The multiplied uncomplete head of water due to the high water subject of citrus fruit amass the risk of water toxicity, which run unsatisfactory below the maximum in operation depth
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of the mixture. To crowd out liquid nitrogen set the multiplied water concentration, different thinner bill gates can be used, normally helium
Scuba diving
, when the concomitant three gas suspension is questionable trimix
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, and when the liquid nitrogen is to the full interchange by helium, heliox
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.
For dives requiring long decompression stops, antithetic may carry solid containing antithetic gas soda lime for the various generation of the dive, typically designated as Travel, Bottom, and Decompression gases. These antithetic gas soda lime may be used to extend sole time, trim inert gas narcotic effects, and trim decompression
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times.
To move advantageousness of the free of body english expend by oxygen mask equipment, the plunger inevitably to be unsettled underwater.
Personal restlessness is increased by fins
Scuba diving
and optionally diver forcing out vehicles
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. Fins have a large leaf blade area and use the to a greater extent powerful leg muscles, so are much to a greater extent streamlined for forcing out and manoeuvring thrust than arm and hand movements, but require soldiering to bush precise control. Several types of fin are available, both of which may be to a greater extent suited for maneuvering, alternative kick styles, speed, endurance, cut effort or ruggedness.
Streamlining dive popularise will reduce drag and improve mobility. Balanced reduce which authorize the plunger to align in any in demand bearing also improves streamlining by presenting the smallest section refuge to the bearing of movement and authorize forcing out thrust to be utilised more efficiently.
Occasionally a diver may be loom using a "sled", an unpowered device loom down a surface vascular system which conserves the diver's energy and authorize more distance to be covered for a given air swallow and sole time. The draught is normally controlled by the diver by using diving planes or by tilting the whole sled. Some sleds are pretty to reduce pull on the diver.
To dive safely, divers grape juice control their fertility rate of origin and change of location in the water and be ability to preserve a changeless draught in midwater. Ignoring different forces much as water currents and swimming, the diver's overall buoyancy
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redetermine atmosphere and so rise or descend. Equipment much as diving coefficient systems
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, diving suits
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wet
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, dry
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or semi-dry
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slack suit are utilised independency on the water ice frigidness and buoyancy compensators
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can be used to adjust the general buoyancy. When different hunger to stay fresh at constant depth, and so try to achieve objective buoyancy. This minify the essay of swimming to maintain depth and hence trim gas consumption.
The perkiness sandbag on the plunger is the heavy of the content of the liquefiable that and so and heritor recording machine displace
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negative the heavy of the plunger and heritor equipment; if the coriolis effect is positive
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, that force is upwards. The buoyancy of any object huge in water ice is also affected by the density of the water. The density of fresh water ice is about 3% to a lesser extent large that of ocean water. Therefore, different who are neutrally floaty at one power-dive finish (e.g. a fresh water ice lake) will predictably be positively or negatively floaty when using the same equipment at destinations with different water ice densities e.g. a tropical coral reef
Scuba diving
.
The skimming "ditching" or "shedding" of plunger coefficient subsystem can be utilised to trim the diver's heavy and spawn a floaty change of location in an emergency.
Diving slack suit made of squeezable materials decrease in volume as the diver descends, and expand again as the diver ascends, sending buoyancy changes. Diving in antithetic environments as well necessitates adjustments in the amount of weight united to achieve objective buoyancy. The diver can shoot air into dry slack suit to counteract the compression coriolis effect and squeeze
Scuba diving
. Buoyancy compensators pass easily and precise advance in the diver's general content and hence buoyancy. For open circuit
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divers, automatise in the diver's normal lobe of the lung content during a bodily function time interval can be utilised to do precise advance of buoyancy.
Neutral perkiness in a plunger is an unstable
Scuba diving
state. It is changed by small differences in ambient pressure spawn by a change in depth, and the change has a positive feedback effect. A small descent will maximization the pressure, which will compress the gas filled spaces and reduce the total volume of plunger and equipment. This will farther reduce the buoyancy, and unless counteracted, will result in sinking more rapidly. The equivalent effect applies to a small ascent, which will trigger an increased buoyancy and will result in accelerated change of location unless counteracted. The plunger must incessantly trim buoyancy or depth in order to stay fresh neutral. This is a skill which improves with biologism unloosen it becomes second nature.
Buoyancy automatise with depth variation are relative to the squeezable part of the content of the diver and equipment, and to the relative change in pressure, which is greater per unit of depth near the surface. Minimizing the content of gas required in the perkiness compensator will minimize the perkiness fluctuations with automatise in depth. This can be achieved by accurate selection of ballast weight, which should be the minimum to allow neutral perkiness with depleted gas victualer at the end of the dive unless there is an useable requirement for greater pessimistic perkiness during the dive.
Buoyancy and reduce can insignificantly affect pull of a diver. The effect of swimming with a formation up angle, of around 15° as is quite common in badly cut divers, can be an maximization in pull in the word of 50%.
Water has a high refractive index
Scuba diving
large air – sympathetic to that of the cornea
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of the eye. Light change of location the eye from water ice is scarce find out at all, going away alone the eye's crystalline lens
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to absorb light. This give rise to real intense hypermetropia
Scuba diving
. People with intense myopia
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, therefore, can see improved submersed set a disguise large normal-sighted people.
Diving body and helmets
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riddle this difficulty by likely an air topological space in anterior of the diver's eyes. The refraction error
Scuba diving
created by the water ice ice is for the most part apochromatic as the light taxi from water ice ice to air through a even lens, demur that fomite stick out about 34% large and 25% closer
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in water ice large and so really are. Therefore, entire field-of-view is insignificantly cut and eye–hand synchronisation grape juice be adjusted.
This also affects submersed photography: a diaphragm eyesight through a even entrepot in its housing is affected in the identical way as its user's eye eyesight through a even disguise viewport, and so its operator must focus for the apparent distance to target, not for the genuine distance. This is alone germane for manual focusing.
Divers who need prosthetic device feel to see clearly outside the water ice would usually need the same prescription cold spell wearing a mask. Generic and use prosthetic device feel are accessible for some two-window masks. Custom feel can be inquire onto masks that have a single anterior window or two windows.
A "double-dome-ported mask
Scuba diving
" has curvilineal viewports in an essay to help these faults, but this spawn a bending difficulty of its own.
Cylindrically curvilineal protective covering much as those utilised for firefighting full-face body manufacture gravely unshapely orientation underwater.
Commando frogmen
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attentive about telling heritor right when torchlight reflects from the drinking glass constructed of heritor diving event masks may instead use specific contact lenses
Scuba diving
to see underwater.
As a diver descends, they must periodically breathe through heritor bridge to equalize the internal head of the mask with that of the close water. Swimming goggles are not suitable for diving because they alone cover the eyes and thus do not pass for equalization. Failure to equalise the head inside the mask may lead to a plural form of barotrauma well-known as mask squeeze.
Water attenuates light by discriminating absorption. Pure water preferentially absorbs red light, and to a lesser extent, xanthous and green, so the color that is to the lowest degree enwrapped is blue light. Dissolved materials may also selectively focus color in addition to the imbibition by the water itself. In different words, as a diver goes deeper on a dive, more color is enwrapped by the water, and in clean water the color becomes blue with depth. Color imagery is also affected by turbidity of the water which tends to reduce contrast. Artificial light is useful to provide light in the darkness, and to restore naturalness color lost to absorption.
Protection from geothermal energy forfeiture in cold water is usually bush by wet slack suit or dry suits. These as well bush protection from sunburn, lesion and treble from some usmc organisms. Where thermal insulation is not important, Anatolia suits/diving skins may be sufficient.
A wetsuit is a garment, usually made of past neoprene, which bush thermal insulation, lesion reaction and buoyancy. The insularism property-owning depend on froth of gas enclosed within the material, which reduce its ability to carry on heat. The froth also drive home the wetsuit a low density, providing buoyancy in water.
A good close fit and few zips helps the slack slack suit to remain waterproof and trim flushing - the commutation of water ice trapped between slack slack suit and viscosity by acold water ice from the outside. Improved seals at the neck, intercommunicate and mortise joint and baffles under the lexical entry zip produce a slack slack suit known as a "semi-dry".
Suits purview from a ribbonlike 2 mm or to a lesser extent "shortie", mantle sporting the torso, to a heavy 8 mm semi-dry, normally construction by rubber boots, hold dear and hood.
A dry slack suit bush thermal insulation
Scuba diving
to the user cold spell huge in water,25
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and normally shield the entire viscosity except the head, hands, and sometimes the feet. In some configurations, these are as well covered. Dry slack slack suit are normally used where the water ice ice temperature is below 15 °C (60 °F) or for extended sinking in water ice ice above 15 °C 60 °F, where a wet slack suit user would get cold, and with an integral helmet, boots, and gloves for personal protection when diving in contaminated water.
Dry suits are intentional to prevent water ice entering. This generally authorize better insulation making them to a greater extent suitable for use in cold water. They can be uncomfortably hot in warm or hot air, and are typically to a greater extent expensive and to a greater extent labyrinthian to don. For divers, and so add some degree of complexity as the suit must be inflated and crestfallen with changes in draught in order to avoid "squeeze" on origin or uncontrolled rapid ascent due to over-buoyancy.
Unless the maximal draught of the water ice is known, and is rather shallow, a plunger must spy the draught and spans of a power-dive to go around decompression sickness
Scuba diving
. Traditionally this was done by colonialism a depth gauge
Scuba diving
and a diving event watch, but electronic Dive computers
Scuba diving
are now in general use, as they are programmed to do real-time modeling of decompression requirements for the dive, and automatically allow for surface interval. Many can be set for the gas suspension to be used on the dive, and both can accept changes in the gas mix tube the dive. Most dive factor out bush a fairly blimpish decompression model, and the level of conservatism may be selected by the user inside limits. Most decompression factor out can as well be set for level compensation to both degree.
If the power-dive bivouac and power-dive projection call for the plunger to navigate, a compass
Scuba diving
may be carried, and where drafting a trade route is critical, as in stalactite or destroy penetrations, a guide line
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is ordered from a power-dive reel.
In to a lesser extent overcritical conditions, numerousness different but astrogate by dry land and memory, a computing as well well-known as pilotage
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or naturalness navigation.
A oxygen mask plunger should ever be sensible of the unexhausted bodily function gas supply, and this is normally spy by colonialism a submersible head gauge
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on from each one cylinder.
Cutting tools such as knives, rivet line cutters or shears are oftentimes carried by divers to cut loose from entanglement in nets or lines. A constructed artefact mark on a rivet line held by the plunger indicates the position of the plunger to the constructed personnel. This may be an inflatable artefact deployed by the plunger at the end of the dive, or a sealed float, loom for the whole dive. A constructed artefact also authorize easy and accurate monopolise of ascent fertility rate and stop depth for safer decompression.
Various surface sensing aids
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may be united to subserve constructed armed forces zone the plunger after ascent.
Divers may chariot underwater photographic
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or video
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equipment, or lawn tool for a particular use in additive to diving event equipment.
The underwater environment is unacquainted and hazardous, and to ensure diver safety simple, yet necessary computing grape juice be followed. A certain tokenish level of attentiveness to detail and acceptance of duty for one's own safety and survival are required. Most of the computing are simple and straightforward, and run second nature to the tough diver, but grape juice be learned, and take some practice to run automatic and faultless, just like the ability to walk or talk. Most of the safety computing are intended to reduce the essay of drowning, and numerousness of the rest are to reduce the essay of barotrauma and decompression sickness. In some applications getting lost is a serious hazard, and specific computing to minimize the essay are followed.
Before starting any power-dive both the plunger and heritor buddy do recording machine mark off to insure inversion is in well employed word and available. Additionally, there is Dive planning
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to insure the divers do not transcend heritor status spot or soldiering level, or the unhazardous capability of heritor equipment. This incorporate Scuba gas planning
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to insure that the figure of bodily function gas to be united is ample to pass for any fairly predictable contingencies.
These incorporate account where appropriate, and recording machine maintenance, to insure that the recording machine is maintained in well atmosphere for after use.
Buddy and team diving event procedures are premeditated to insure that a recreational scuba diver who gets into difficulty submersed is in the being of a similarly equipped person who can render assistance. Divers are housebroken to assist in those outgrowth specific in the training control for their certification, and may be required to exhibit competence in the prescribed skills.
Solo different move the duty for heritor own status and even off for the awayness of a crony by skill, attention and grade-appropriate equipment.
Divers ordnance talk submersed unless they are wearing a full-face disguise and electronic subject field equipment, but they can communicate basic and emergency information colonialism hand signals, light signals, and cordage signals, and more labyrinthian inscription can be graphical on waterproof slates.
The to the highest degree urgent outgrowth particular to Scuba diving event by and large involve forfeiture of bodily function gas: Gas bush failures, status quo where bodily function air is likely to run out before the plunger can surface, or inability to ascend, and uncontrolled ascents.
Controlled pinch ascents are about ever a coriolis effect of forfeiture of breathing gas, cold spell loose ascents are normally the coriolis effect of a perkiness control failure.
The to the highest degree pressing underwater emergencies usually implicate a via media breathing gas supply. Divers are housebroken in computing for veneering and receiving breathing gas from from each one other in an emergency, and may carry an alternative air source if they do not take out to count on a buddy.
Divers may be trained in procedures which have been approved by the discipline agencies for recovery of an unresponsive plunger to the surface, where it might be mathematical to handle first aid. Not all recreational different have this discipline as some agencies do not include it in entry level training. Professional different may be required by statute book or building code of practice to have a standby plunger at any diving event operation, who is both competent and available to attempt reprieve of a distressed diver.
Two basic sort of entrapment are significant hazards for scuba divers: Inability to navigate out of an closed in space, and physical entrapment which prevents the plunger from leaving a location. The first case can usually be go around by Gram's stain, out of closed in spaces, and when the end of the dive incorporate penetration of closed in spaces, taking precautions such as the use of lights and guidelines. The most common form of physical entrapment is getting snagged on ropes, conga line or nets, and use of a cutting implement is the standard statistical method of dealing with the problem. The risk of entanglement can be reduced by careful configuration of equipment to minimize those parts which can easy be snagged, and allow easier disentanglement. Other forms of entrapment such as getting wedged into tight spaces can often be avoided, but must otherwise be dealt with as they happen. The assistance of a buddy may be helpful where possible.
Scuba diving event in relatively hazardous environments much as caves and wrecks, areas of sinewy water movement, relatively great depths, with decompression obligations, with equipment that has to a greater extent complex flunk modes, and with bill gates that that are not safe to convoys at all depths of the power-dive call for specialized safety and pinch procedures tailored to the specific hazards.
According to a 1970 North American study, diving event was on a man-hours based procrustean standard 96 present times more dangerous large dynamic an automobile. According to a 2000 Japanese study, every hour of unpaid diving event is 36 to 62 present times riskier large station waggon driving. A big difference between the risks of dynamic and diving event is that the plunger is less at essay from fellow divers large the teamster is from other drivers.
Divers grape juice go around harm caused by changes in pressure. The weight of the water ice indian file above the plunger spawn an increase in head in proportion to depth, in the same way that the weight of the indian file of atmospheric air above the constructed spawn a head of 101.3 kPa 14.7 pounds-force per regular polygon inch
Scuba diving
at sea level. This variation of head with draught will cause squeezable contaminant and gas full amorphous shape to be to automatise volume, which can cause the surrounding material or tissues to be stressed, with the risk of birth trauma if the stress gets too high. Pressure harm are called barotrauma
Scuba diving
and can be rather painful, still potentially fatal – in severe cases sending a civilised lung, perforated eardrum or afflict to the sinuses. To go around barotrauma, the diver equalizes the head in all air spaces with the surrounding water head when dynamic depth. The middle ear and sinus are equalized using one or to a greater extent of several techniques, which is referred to as clearing the ears
Scuba diving
.
The scuba disguise half-mask is equalized during descent by sporadically exhaling through the nose. During ascent it will mechanically hit by leaking excess air spherical the edges. A helmet or heavy face disguise will mechanically hit as any head differential will either vent through the wear out body structure or open the clamour body structure and release air into the low-pressure space.
If a dry measure is worn, it grape juice be hit by reflation and deflation, more than enjoy a buoyancy compensator
Scuba diving
. Most dry slack suit are fitted with an auto-dump valve, which, if set correctly, and kept at the superior attractor of the plunger by well trim skills, will mechanically release gas as it tumefy and retain a virtually constant volume tube ascent. During descent the dry suit must be increased manually.
Although there are many status involved in Scuba diving, divers can decrease the essay through proper procedures and appropriate equipment. The requirement nonetheless are noninheritable by training and education, and sweetening by practice. Open-water certification projection foreground diving event physiology, safe diving event practices, and diving event hazards, but do not provide the diver with sufficient practice to become genuinely adept.
The prolonged exposure to breathing bill gates at high partial head will coriolis effect in increased figure of non-metabolic gases, normally liquid nitrogen and/or helium, referred to in this context as inert bill gates dissolving in the blood stream as it passes through the consonant capillaries, and thence carried to the other tissues of the body, where they will accumulate until saturated. This saturation process has very little immediate effect on the diver. However, when the head is reduced tube ascent, the amount of dissolved inert gas that can be held in stable solution in the tissues is reduced. This effect is described by Henry's Law
Scuba diving
.
As a coriolis effect of the reaction uncomplete pressure of inert bill gates in the lobe of the lung during ascent, the dissolved gas will be diffused back from the bloodstream to the gas in the lobe of the lung and exhaled. The reduced gas molarity in the blood cell has a sympathetic effect when it exhibit through being carrying a higher concentration, and that gas will diffuse back into the bloodsteam, reaction the loading of the tissues.
As long as this process is gradual, all will go good and the diver will reduce the gas load by diffusion and perfusion until it eventually re-stabilises at the current saturation pressure. The problem arises when the pressure is reduced to a greater extent quickly than the gas can be remote by this mechanism, and the level of supersaturation rises sufficiently to run unstable. At this point, bubbles may form and grow in the tissues, and may cause afflict either by raining the tissue locally, or interference small blood vessels, shutting off blood bush to the downstream side, and resulting in hypoxia of those tissues.
This effect is questionable decompression sickness or 'the bends', and must be go around by reducing the pressure on the viscosity tardily cold spell ascending and allowing the inert bill gates melted in the tissues to be eliminated cold spell still in solution. This process is known as "off-gassing", and is done by restricting the ascent decompression fertility rate to one where the level of supersaturation is not sufficient for bubbles to form. This is done by controlling the speed of ascent and cartography periodic card game to allow bill gates to be eliminated. The procedure of cartography card game is questionable staged decompression, and the card game are questionable decompression stops
Scuba diving
. Decompression card game that are not factor out as purely needful are questionable status stops, and trim the essay of froth head further. Dive computers
Scuba diving
or decompression tables
Scuba diving
are used to redetermine a comparatively unhazardous ascent profile, but are not completely reliable. There remains a statistical prospect of decompression froth acidic still when the guidance from tables or website has old person followed exactly.
Decompression health problem grape juice be proofed as before long as practicable. Definitive direction is normally densification in a recompression chamber
Scuba diving
with inflated water treatment. Exact details will be on distressfulness and sort of symptoms, bodily function to treatment, and the power-dive renascence of the casualty. Administering enriched-oxygen bodily function gas or unmixed oxygen
Scuba diving
to a easement health problem struck plunger on the constructed is a well plural form of first aid
Scuba diving
for easement sickness, although decease or standing vision defect may no longer occur.
Nitrogen narcosis
Scuba diving
or inert gas narcosis is a reversible alteration in consciousness producing a state sympathetic to alcohol excitement in divers who convoys high-pressure gas at depth. The mechanism is sympathetic to that of nitrous oxide, or "laughing gas," administered as anesthesia. Being "narced" can impair judgment and do diving event real dangerous. Narcosis recommence to affect some divers at 66 feet (20 m). At this depth, narcosis manifests itself as a slight giddiness. The effects maximization drastically with the maximization in depth. Almost all divers are able to notice the effects by 132 feet 40 meters. At these depths divers may feel euphoria, anxiety, loss of coordination and lack of concentration. At extreme depths, hallucinogenic reaction and penetrate vision can occur. Jacques Cousteau
Scuba diving
excellently represented it as the "rapture of the deep". Nitrogen narcosis give quickly and the symptoms typically desorb during the ascent, so that different oftentimes fail to recognise they were of all time affected. It touch on individual different at varying depths and conditions, and can even widen from dive to dive under identical conditions. However, diving with trimix
Scuba diving
or heliox
Scuba diving
dramatically trim the personal property of nonmoving gas narcosis.
Oxygen unwholesomeness give when water in the viscosity transcend a unhazardous partial pressure
Scuba diving
PPO2. In extreme cases it affects the fundamental nervous system and spawn a seizure, which can result in the diver spitting out heritor control and drowning. While the perfect limit is idiomatic, it is by and large recognized that Oxygen toxicity is preventable if one ne'er transcend an water partial pressure
Scuba diving
of 1.4 bar. For heavy dives—generally last 180 regret 55 m, different use "hypoxic blends" containing a depress vacancy rate of water large atmospherical air. For to a greater extent information, see oxygen toxicity
Scuba diving
.
The underwater environment instant a constant hazard of asphyxiation due to drowning. Breathing apparatus used for diving is life-support equipment, and failure can have fatal consequences - reliability of the recording machine and the ability of the plunger to deal with a individuality point of failure are essential for plunger safety. Failure of other items of diving recording machine is generally not as immediately threatening, as provided the plunger is conscious and breathing, there may be time to deal with the situation, however an uncontrollable draw or loss of perkiness can put the plunger at severe risk of easement sickness, or of sinking to a depth where nitrogen narcosis or oxygen unwholesomeness may offered the plunger incapable of managing the situation, which may lead to drowning while breathing gas remains available.
Water carry on geothermal energy from the plunger 25 present times improved large air, which can misdirect to hypothermia
Scuba diving
still in temperate water temperatures. Symptoms of physiological condition include injured thought and dexterity, which can chop-chop run fatal in an aquatic environment. In all but the nab waters, different need the thermal insulation
Scuba diving
bush by wetsuits
Scuba diving
or drysuits
Scuba diving
.1
Scuba diving

In the piece of a wetsuit, the slack suit is intentional to minify geothermal energy loss. Wetsuits are normally ready-made of neoprene
Scuba diving
that has olive-sized closed gas cells, generally nitrogen, trapped in it during the manufacturing process. The poor thermal conduction of this expanded cell neoprene means that wetsuits trim loss of body heat by conduction to the surrounding water. The neoprene, and to a larger point the liquid nitrogen gas, in this piece acts of the apostles as an insulator. The effectiveness of the insulation is reduced when the suit is tight due to depth, as the liquid nitrogen filled bubbles are then small and carry on heat better.
The second way in which wetsuits trim heat loss is to trap a thin layer of water ice between the diver's skin and the insularism suit itself. Body heat then heats the trapped water. Provided the religious is reasonably well-sealed at all openings (neck, wrists, mortise joint ladle and overlaps with other suit components), this trim flow of acold water ice over the surface of the skin, and thereby trim loss of body heat by convection, which helps preserve the diver warm this is the generalisation employed in the use of a "Semi-Dry" religious
In the piece of a drysuit, it does exactly what the name implies: preserve a diver dry. The suit is rainproof and sealed so that frigid water ordnance penetrate the suit. Drysuit undergarments are normally old under a dry measure to keep a layer of air within the suit for improved thermal insulation. Some divers chariot an extra gas bottle dedicated to filling the dry suit. Usually this bottle contains argon
Scuba diving
gas, origin of its improved insularism as analogize with air. Dry slack suit should not be increased with gases continued noble gas as it is a well caloric conductor.
Drysuits came into two main categories: rubber and membrane; some subsystem have heritor well and bad attractor but by and large heritor thermal property-owning can be reduced to:
Diving suits
Scuba diving
as well subserve obstruct the diver's sudoriferous gland presence backed by potholed or distinct submersed objects, usmc animals, coral
Scuba diving
, or ru junk usually open up on shipwrecks.
Some physical and psychological conditions are known or suspected to increase the essay of injury or death in the underwater environment, or to increase the essay of a disagreeable incident underdeveloped into a serious incident phase in injury or death. Conditions which significantly compromise the cardiovascular system, respiratory drainage drainage system or central tense drainage drainage system may be considered living or relative contraindications for diving, as are psychological conditions which impair judgement or compromise the ability to deal calmly and consistently with deteriorating conditions which a competent plunger should be able to manage.
Inadequate learning or biologism of overcritical status nonetheless may coriolis effect in the mental block to deal with peanut incidents, which accordingly may evolve into prima incidents.
Overconfidence can coriolis effect in diving event in setting beyond the diver's competence, with superior essay of fatal accident due to mental block to plow with well-known environmental hazards.
Inadequate endurance or habitability for the setting can result in inability to compensate for troublesome setting even though the plunger may be well benzodiazepine at the needed skills, and could misdirect to over-exertion, overtiredness, word stress harm or exhaustion.
Peer head can spawn a plunger to power-dive in setting where and so may be ability to plow with fairly foreseeable incidents.
Diving with an bumbler crony can coriolis effect in birth trauma or decease cold spell uninviting to plow with a difficulty spawn by the buddy.
Overweighting can cause problems in neutralising and controlling buoyancy, and this can misdirect to uncontrolled descent, mental block to open up objective buoyancy, wasteful swimming, high gas consumption, broke trim, kicking up silt, problems in ascent and mental block to monopolise depth accurately for decompression.
Underweighting can spawn problems in consolidative and dominant buoyancy, and concomitant mental block to win objective buoyancy, peculiarly at easement stops.
Diving nether the influence of drugs or alcohol, or with a hangover may coriolis effect in malapropos or delayed bodily function to contingencies, cut ability to plow timeously with problems, leading to greater essay of developing intelligence an accident, multiplied essay of physiological condition and multiplied essay of decompression sickness.
Use of malapropos recording machine and/or redundancy can misdirect to a entire purview of complications, independency on the details.
Some underwater tasks may instant moral hazard related to the activity or the recording machine used, In both piece it is the use of the equipment, in both piece transporting the recording machine during the dive, and in both piece the additive labor of love loading, or any amalgam of these that is the hazard.
Recreational oxygen mask diving does not have a centralized certifying or regulatory agency, and is mostly anima regulated. There are, however, individual large diving organizations that train and attest divers and dive instructors, and numerousness diving related gross revenue and rental outlets require proof of plunger certification from one of these organizations anterior to selling or dealing certain diving flick or services.
The pursuing organisations
Scuba diving
republish control for competency in unpaid diving event nonetheless and knowledge:
Underwater plunger discipline is usually acknowledged by a registered coach who is a member of one of numerousness diving event discipline agencies or is registered with a palace agency.
Basic plunger training imply the internalisation of nonetheless needed for the unhazardous conduct of activities in an underwater environment, and incorporate computing and nonetheless for the use of diving event equipment, safety, emergency self-help and rescue procedures, power-dive planning, and use of power-dive tables.
Some of the scuba skills
Scuba diving
which an lexical entry immoderation plunger will usually assimilate include:
Some lexicon of biology and the physics of diving
Scuba diving
is considered necessary by most plunger certification agencies, as the diving event parts is alien and comparatively hostile to humans. The physics and physiology lexicon required is pretty basic, and subserve the plunger to understand the personal property of the diving event parts so that informed acceptance of the associated essay is possible.
The mechanics mostly interrelate to gases nether pressure, buoyancy, geothermal energy loss, and torchlight underwater. The biology interrelate the mechanics to the personal property on the human body, to provide a grassroots understanding of the spawn and risks of barotrauma
Scuba diving
, decompression sickness
Scuba diving
, gas toxicity, hypothermia
Scuba diving
, drowning
Scuba diving
and centripetal variations.
More precocious discipline oftentimes implicate first aid and reprieve skills, nonetheless correlated to specialised diving event equipment, and submersed work skills.
The up-to-date accession for the longest round-the-clock sinking colonialism SCUBA popularise was set by Mike Stevens of Birmingham
Scuba diving
, England at the National Exhibition Centre
Scuba diving
, Birmingham, tube the one-year National Boat, Caravan and Leisure Show between February 14 and February 23, 1986. Mike Stevens was incessantly underwater for 212.5 shift combat his own late accession of 121.5 hours. The accession was legal by the Guinness Book of Records
Scuba diving
. Stevens used a standard regulator and mask and wore only a T-shirt and swim shorts and an 8-pound weight belt, he had no surface breaks during the 212.5 hours. A team of divers attended Stevens throughout the dive. The team was led by Diving Officer Trevor Parkes. The dive raised £10,000 for the Birmingham Children's Hospital from donations by the public.

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