Modes of underwater diving

{{Short description|Techniques requiring specific equipment and procedures}} {{good article}} {{distinguish|Dive mode (dive computer)|text=the "dive mode" option on a dive computer}} thumb|Two very different modes of diving: Ambient pressure open circuit scuba diving (left) and atmospheric pressure diving in a pressure resistant suit (right) A '''mode of diving''', or '''diving mode''', is a particular way to dive underwater that requires specific equipment, procedures and techniques, and may expose the diver to a particular range of hazards.<ref name="Hong Kong" />

There are several modes of diving; these are distinguished by the type of breathing apparatus, diving equipment, procedures and techniques involved, and whether the diver is exposed to ambient pressure.<ref name="Hong Kong" /> ''Ambient pressure diving'' includes freediving and compressed-gas diving,<ref name="Mitchell et al 2012" /><ref name="Loudoun" /> which may also be classed as ''air diving'', ''oxygen diving'', and ''mixed gas diving'' by the breathing gas used, and as ''open-circuit'', ''semi-closed'', or ''closed-circuit'' depending on the type of breathing apparatus used. There is also ''atmospheric pressure diving'', which involves encapsulation in an atmospheric pressure diving suit or submersible,<ref name="Thornton 2000" /> and ''unmanned diving'', where there are no human divers involved. The diving equipment, support equipment and procedures used largely depend on the mode of diving.<ref name="Hong Kong" />

In certain circumstances, some modes of diving may be impracticable, unsafe, not permitted by the governing organisation, or illegal.<ref name="IMCA D014" /><ref name="Diving at Work Regulations 1997" /> All modes of diving carry a certain amount of risk; this is mitigated with planning, training, and the appropriate equipment.<ref name="Hong Kong" />

==Ambient pressure diving==  Ambient pressure diving modes are those in which the diver is exposed to the ambient pressure in the water due to combined hydrostatic and local atmospheric pressure.<ref name="Hong Kong" />

Ambient pressure diving can also be classified as surface-oriented diving, where the diver is decompressed to surface ambient pressure at the end of each dive, and saturation diving, where the diver remains under pressure between in-water exposures.{{sfnp|''US Navy Diving Manual''|2006|loc=Chapter 15 Saturation Diving}} There is also a distinction between freediving, where the diver holds their breath, and compressed-gas diving, where the diver breathes gas at ambient pressure during the dive.<ref name="BSAC Sport Diving" /><ref name="Mitchell et al 2012" />

They may be further classified by the type of breathing apparatus used, and by the level of confinement of the diving environment.

=== Surface-oriented (bounce) diving === {{see also|Surface-oriented diving}} Professional divers refer to diving where the diver starts and finishes the diving operation at atmospheric pressure as surface-oriented, or bounce diving.<ref name="Rekdal 2004" /> In recreational diving there is no need to make this distinction, as all recreational diving is surface-oriented, usually without decompression stops.<ref name="ADAS" /><ref name="businessofdiving" />The diver may be deployed from the shore or a diving support vessel and may be transported on a diving {{Diving term|stage}} or in a diving bell. Surface-supplied divers almost always wear diving helmets or full-face diving masks. The bottom gas can be air, nitrox, heliox or trimix; the decompression gases may be similar, or may include pure oxygen.<ref name="Imbert 2006" /> Decompression procedures include in-water decompression or surface decompression in a deck chamber.{{sfnp|''US Navy Diving Manual''|2006|loc=Chapter 9 Air Decompression}} Surface oriented dives may use a transportation platform to move the diver vertically through the water column, may be assisted by an attendant controlling the umbilical, or the diver may control their own descent and ascent.<ref name="Hong Kong" />

==== Freediving ==== thumb|Recreational breath-hold divers in basic equipment with floats and catch bags suitable for collecting lobster or shellfish|alt= A croup of three divers dressed in wetsuits standing on a rocky shore with the sea in the background. On the ground are inflated truck inner tube floats with nets to support their catch {{main|Freediving}} The ability to dive and swim underwater while holding one's breath is considered a useful emergency skill, an important part of water sport and navy safety training, and an enjoyable leisure activity.<ref name="BSAC Sport Diving" /> It is the original diving mode.<ref name="UW360" /> Underwater diving without breathing apparatus can be categorised as underwater swimming, snorkelling and freediving; these categories overlap considerably. Several competitive underwater sports are practised without breathing apparatus.<ref name="Aquathon" /><ref name="Apnoea" /><ref name="Hockey" /><ref name="Rugby" /><ref name="Spearfishing" />

Freediving excludes the use of underwater breathing apparatus, and relies on the ability of divers to hold their breath until resurfacing. The technique ranges from simple breath-hold diving to competitive apnea dives. Swimfins and a diving mask are often used in free diving to provide more efficient propulsion and improve underwater vision. A short breathing tube called a snorkel allows the diver to breathe at the surface while the face is immersed.<ref name="BSAC Sport Diving" /><ref name=NPAL />

==== Scuba diving ==== {{multiple image | total_width = 450 | header_align = center | header = Scuba diving in open circuit and rebreather modes | image1 = DIR Divers Sandra edwards 2010.JPG | alt1 = Two divers swim over a rocky reef in clear water. They are trimmed level and show good technique | caption1 = Recreational scuba divers on open circuit | width1 = 517 | height1 = 384 | image2 = US Navy explosive ordnance disposal (EOD) divers.jpg | alt2 = A diver appears to work on a large spherical mine, with another diver observing from a distance in the background | caption2 = Explosive ordnance disposal divers using rebreathers | width2 = 1089 | height2 = 1421 }} {{Main|Scuba diving}}  Scuba diving is a mode of compressed-gas diving with a self-contained underwater breathing apparatus, which is completely independent of surface supply. Scuba gives the diver mobility and horizontal range far beyond the reach of an umbilical hose attached to surface-supplied diving equipment (SSDE), and much greater endurance than freediving.{{sfnp|''US Navy Diving Manual''|2006|loc=Chapter 1 Section 3 Scuba Diving}}

===== Open circuit scuba ===== Open circuit scuba systems discharge breathing gas into the environment as it is exhaled, and consist of one or more diving cylinders containing pressurized breathing gas, supplied to the diver at ambient pressure through a diving regulator. They may include additional cylinders for decompression gas or emergency breathing gas.{{sfnp|''NOAA Diving Manual''|2001|loc=Chapter 5 Section 4 Emergency Air Supply}}

===== Scuba rebreather ===== {{Main|Rebreather diving}}

Closed-circuit or semi-closed circuit rebreather scuba systems allow the recycling of exhaled gases; the volume of gas used is reduced compared to that of open circuit, so smaller cylinders may be used for an equivalent dive duration. They allow a diver to spend much more time underwater while consuming the same amount of gas. Rebreathers produce fewer bubbles and less noise than scuba, which makes them attractive to covert military divers to avoid detection, to scientific divers to avoid disturbing marine animals, and to media divers to avoid bubble interference.{{sfnp|''US Navy Diving Manual''|2006|loc=Chapter 17 Section 1 Introduction}}

==== Surface-supplied diving ==== {{multiple image | total_width = 450 | header_align = center | header = Surface-supplied diving in surface-oriented and saturation modes | image1 = U.S. Navy Diver enters the water during a training evolution at the Naval Diving and Salvage Training Center 140218-N-IC111-156.jpg | alt1 = A US Navy surface supplied diver wearing a lightweight demand helmet and holding the umbilical at head level is shown entering the water by jumping in. The view is from the deck from which the diver has jumped, and shows the back of the diver as the fins first contact the water | caption1 = Surface-oriented diver entering the water | width1 = 2000 | height1 = 3000 | image2 = US Navy 010707-N-3093M-003 Diver Transfer Capsule.jpg | alt2 = Night view of a white spherical pressure chamber in a blue pipe frame supporting several blue bulk gas storage clinders, suspended over the water by cables. The bell umbilical is visible at the top and a ballast weight can be seen below at the water surface | caption2 = Closed diving bell, also known as a diver transfer capsule | width2 = 1500 | height2 = 2100 }} {{main|Surface-supplied diving}}  An alternative to self-contained breathing systems is to supply breathing gases from the surface through a hose. When combined with a communication cable, a pneumofathometer hose and a safety line it is called the diver's umbilical, which may also include a hot water hose for heating, video cable and breathing gas reclaim line. The diver generally wears a full-face mask or helmet, and gas may be supplied either on demand or at a constant, continuous rate. More basic equipment that uses only an air hose is called an airline or hookah system.<ref name="CoP Inshore" />{{sfnp|''NOAA Diving Manual''|2001|loc=Chapter 5 Diver and Diving Support Equipment}}<ref name="Eleftheriou 2013" /> This allows the diver to breathe using an air supply hose from high pressure cylinders or a diving air compressor at the surface. Breathing gas is supplied through a mouth-held demand valve or light full-face mask. Airline diving is used for work such as hull cleaning and archaeological surveys, for shellfish harvesting, and as snuba, a shallow water activity typically practised by tourists and those who are not scuba-certified.<ref name="Eleftheriou 2013" /><ref name="Huffington 2014" /><ref name="snuba" />

===== Stage diving ===== thumb|Diving stage {{see also|Decompression equipment#Diving stages and wet bells|Surface-supplied diving skills#Stage diving procedures}}  Stage diving may refer to surface-supplied diving from a diving stage, or technical scuba diving where stage cylinders are used for different stages of a long dive, and may contain different gases.<ref name="Rigging stage bottles" />  A diving stage or diving basket is a simple platform lowered and lifted from the surface platform by a winch under the control of the diving team. The diver's umbilical leads directly to the diver and is managed at the surface by the diver's attendant.<ref name="Hong Kong" /> In-water decompression is facilitated as the stage can be hoisted at a controlled rate and held at reasonably constant depths for stops.<ref name="IDSA" />

===== Open bell diving =====  thumb|Diver under a wet bell at the surface site {{see also|Diving bell#Open bells}} Open bell diving uses an ambient pressure diving bell to transport the diver through the water column. A wet bell with a gas filled dome provides more comfort and control than a stage and allows for longer time in water. Wet bells can be used for air and mixed gas diving, and divers can decompress on oxygen at {{convert|12|m|ft|-1}}.<ref name="Imbert 2006" />

===== Closed bell bounce diving ===== {{see also|Bell-bounce diving|Transfer under pressure diving}} Small closed bell systems have been designed that can be easily mobilised, and include a two-man bell, a launch and recovery system and a chamber for decompression after transfer under pressure (TUP). Divers can breathe air or mixed gas at the bottom and are usually recovered with the chamber filled with air. They decompress on oxygen supplied through built in breathing systems (BIBS) towards the end of the decompression. Small bell systems support bounce diving down to {{convert|120|m|ft}} and for bottom times up to 2 hours. Larger closed bells can be used the same way and also for saturation diving with up to three divers, including a bellman.<ref name="Imbert 2006" /><ref name="USNDM R6" />

===== Scuba replacement ===== {{See also|Scuba replacement}} A relatively portable surface gas supply system using high pressure gas cylinders for both primary and reserve gas, but using the full diver's umbilical system with pneumofathometer and voice communication, is known in the industry as "scuba replacement". It is generally used where scuba equipment cannot be used for reasons of safety or when it is not allowed by regulations or code of practice, and full surface supplied equipment is inconvenient, impractical, or unsafe. A lightweight helmet or full-face mask and bailout cylinder are standard for this mode<ref name="IMCA D014" />

===== Air-line diving ===== {{Further|Air-line diving}} thumb|Low pressure breathing air compressor intended for air-line diving Hookah, {{Diving term|Sasuba}} and Snuba systems are categorised as "air-line" equipment, as they are supplied through a basic air line, and do not include the communication, lifeline and pneumofathometer hose characteristic of a full diver's umbilical. A bailout system is not an inherent part of an air-line diving system, though it may be required in some applications.<ref name="FAO Hookah" /><ref name="scubadoc hookah" />

Their field of application is very different from full surface-supplied diving. Hookah is generally used for shallow water work in low-hazard applications, and sometimes for open water hunting and gathering of seafood,<ref name="FAO Hookah" /> shallow water mining of gold and diamonds in rivers and streams, and bottom cleaning and other underwater maintenance of boats, hull cleaning, swimming pool maintenance, and shallow underwater inspections.<ref name="Barsky and Neuman 2003" /><ref name="businessofdiving" />

Sasuba and Snuba are a shallow water recreational application for low-hazard sites, using air supplied through a short hose of about 7 m to a demand valve mouthpiece.<ref name="seattle1995" />

===== Compressor diving ===== Compressor diving is a rudimentary method of surface-supplied diving used in some tropical regions such as the Philippines and the Caribbean. The divers swim with a half mask and fins and are supplied with air from an industrial low-pressure air compressor on the boat through plastic tubes. There is no reduction valve; the divers hold the hose ends in their mouths with no demand valve or mouthpiece and allow excess air to spill out between the lips.<ref name="Into the Blue" />

=== Saturation diving === thumb|US Navy modular saturation system during manned testing thumb|Saturation diving support vessel Iremis da Vinci. |alt=A red hulled ship seen from the port quarter at a low angle. It has heavy lifting gear on the quarterdeck and a helipad over the forecastle. {{Main|Saturation diving}} Saturation diving lets professional divers live and work under pressure for days or weeks at a time. After working in the water, the divers rest and live in a dry pressurised underwater habitat on the bottom or a saturation life support system of pressure chambers at the surface, usually on the deck of a diving support vessel, oil platform or other floating platform, at a similar pressure to the ambient pressure at the work depth. They are transferred between surface accommodation and the underwater workplace in a pressurised closed diving bell. Decompression at the end of the dive may take many days, but since it is done only once for a long period of exposure, rather than after each of many shorter exposures, the overall risk of decompression injury to the diver and the total time spent decompressing are reduced. This type of diving allows greater work efficiency and safety.{{sfnp|''US Navy Diving Manual''|2006|loc=Chapter 15 Saturation Diving}}

=== Modes of breathing gas management === {{main|Underwater breathing apparatus}} There are three basic modes of breathing gas management available for use in both self-contained (scuba) and surface-supplied underwater breathing apparatus for ambient pressure diving.<ref name="Hong Kong" /><ref name="USNDM R6" />

==== Open-circuit ==== thumb| Diving with a recreational open-circuit scuba set Open circuit diving uses breathing apparatus which discharges exhaled breathing gas directly into the environment. The simplest case of this system is {{visible anchor|constant oxygen fraction or constant gas fraction diving}}, when the same breathing gas mixture is used throughout the dive. However, open circuit can also be used with gas switching, where the breathing gases used on different stages of the dive are changed to better suit the depth and decompression requirements. Air diving is the classic example of single gas open circuit diving, but most recreational diving and shallow surface-supplied diving falls under this mode. Open circuit systems may provide gas by constant flow or supply on demand, and some equipment can be switched between these modes by the diver.<ref name="USNDM R6" />

==== Closed-circuit ==== thumb|Diver using closed circuit rebreather  A closed-circuit apparatus recirculates breathing gas indefinitely, with carbon dioxide removed and oxygen added, generally to maintain a constant partial pressure, regardless of depth. This is also called {{visible anchor|constant oxygen partial pressure diving}} and is a feature of electronically controlled closed circuit rebreathers (eCCR)<ref name="USNDM R6" /> Gas reclaim systems and push-pull diving systems are forms of closed circuit gas recycling equipment not carried by the diver, used mainly to recover expensive helium-based diluent gases.<ref name="P D Handbook 5.3" /><ref name="DH Divex" /><ref name="arawak" />

==== Semi-closed-circuit ==== A semi-closed-circuit apparatus partly recycles the breathing gas mixture. Oxygen partial pressure is maintained at a breathable level by addition of breathing gas mixture at a rate sufficient to make up the losses due to exhaust gas and metabolism. The oxygen concentration is not constant, but varies between predictable limits. The equipment used for this may be called a semi-closed circuit rebreather or a gas extender. Such systems have been used in scuba rebreathers,<ref name="TDISDI" /> and surface supplied and self-contained free-flow helmet equipment.<ref name="Diving heritage Deep" /><ref name="Desco Helium" />

=== Mode by breathing gas ===  {{see also|Breathing gas#For diving and other hyperbaric use}} The original breathing gas for diving was atmospheric air, and compressed air remains an important breathing gas for ambient pressure diving. Oxygen is limited to shallow water to avoid toxicity problems, and is usually used to accelerate decompression, or in closed circuit rebreathers by tactical divers to provide a long endurance with a small amount of gas, and to minimise bubbles where detection would be a tactical problem. Some physiological problems of deeper diving, such as inert gas narcosis and high work of breathing, can be mitigated by the use of breathing gases based on helium, and experimental work which includes hydrogen in the mixture for extreme depths, continues.<ref name="Fogarty 2020" /> The common terminology refers to air diving and gas diving,<ref name="Air diving system" /><ref name="ADAS Air diving" /> which includes oxygen diving,<ref name="mixed gas and oxygen" /> and mixed gas diving, which includes nitrox diving, trimix diving, and heliox diving.<ref name="Lee et al 2020" /><ref name="mixed gas and oxygen" />

Air is available for the cost of operating the compressor, so it is supplied on open circuit, and discharged into the surroundings on exhalation, and may be supplied through a free-flow system where this has advantages. Oxygen and nitrox are also cheap enough that it is usually economical to supply by demand open circuit except for long duration scuba operations, but helium is expensive and sometimes in short supply, so recycling can be viable for moderate usage, and essential for high volume usage. The costs of recycling by rebreathing or reclaiming helium based gases include high capital investment in the equipment, and additional running costs compared to open circuit.<ref name="P D Handbook 5.3" /> The use of hydrogen as a breathing gas component is still experimental.<ref name="Fogarty 2020" />

=== Modes of decompression === {{see also|Decompression practice#Modes of decompression}} Decompression is a part of every ambient pressure dive. Modes of decompression range from "no-stop dives" where a limited and controlled ascent rate is sufficient decompression,<ref name="Gibb" /> to decompression from saturation over several days.<ref name="USNDM R6" />

Decompression can be continuous, where no stops are required, and the rate of ascent is limited to provide sufficient time to outgas safely,<ref name="USNDM R6" /> or staged, where ascent is made up to and between stops a limited rate, but most of the outgassing occurs during periods of constant depth, (pressure) called decompression stops. Continuous decompression rates depend on the theoretical gas loading of the controlling tissue, and may be fixed or, more often, variable with depth.<ref name="USNDM R6" />

Decompression can also be done entirely in the water, partly in the water and partly in a surface decompression chamber or entirely in one or more decompression chambers. It can also be classified by the type of breathing gases used while decompressing, whether there are changes in gas composition during decompression, and whether the changes are stepwise or continuous, or a combination of both.<ref name="USNDM R6" />

Air diving traditionally uses air as breathing gas for the entire dive, including for in-water staged decompression. It is simple, low cost, requires little or no special equipment, but is inefficient and limited to tolerable in-water exposures.<ref name="USNDM R6" />

Modes of decompression: *{{annotated link|No-stop decompression}}<ref name="USNDM R6" /> *{{annotated link|Continuous decompression}}<ref name="USNDM R6" /> *{{annotated link|Staged decompression}}<ref name="USNDM R6" /> *{{annotated link|Accelerated decompression}}<ref name="USNDM R6" /> *{{annotated link|Repetitive dive decompression}}<ref name="USNDM R6" /> *{{annotated link|Altitude decompression}}<ref name="USNDM R6" /> *{{annotated link|Gas switching}}<ref name="Doolette and Mitchell 2013" /> *{{annotated link|Surface decompression}}<ref name="USNDM R6" /> *{{annotated link|Closed bell decompression}}<ref name="Imbert 2006" /> *{{annotated link|Transfer under pressure decompression}}<ref name="Risberg et al 2023" /> *{{annotated link|Saturation decompression}}<ref name="USNDM R6" /> *{{annotated link|Therapeutic decompression}}<ref name="USNDM R6" />

==Atmospheric pressure diving== {{main|Atmospheric diving suit}}

{{multiple image | total_width = 450 | header_align = center | header = Atmospheric pressure suit and submersible modes | image1 = Navy Diver4.jpg | alt1 = A diver in an armoured diving suit stands on a launch and recovery platform on the support vessel, attended by a crewman. | caption1 = US Navy Atmospheric Diving System (ADS) | width1 = 1488 | height1 = 2240 | image2 = Limiting Factor to be prepared for a dive into the Atlantic Ocean.jpg | alt2 = A large support vessel with a small rectangular profile deep submergence vehicle suspended over the water at the stern | caption2 = Full ocean depth rated DSV ''Limiting Factor'' prepared for a dive into the Atlantic Ocean | width2 = 2400 | height2 = 1349 }}

Submersibles and rigid atmospheric diving suits (ADS) enable diving to be carried out in a dry environment at approximately surface atmospheric pressure. An ADS is a small one-person articulated submersible which resembles a suit of armour, with elaborate joints to allow bending, while maintaining an internal pressure of one atmosphere. An ADS can be used for dives of up to about {{convert|700|m|ft}} for many hours. It eliminates the majority of physiological dangers associated with deep diving – the occupant does not need to decompress, there is no need for special gas mixtures, and there is no danger of nitrogen narcosis – at the expense of higher cost, complex logistics and loss of dexterity.<ref name="subsea 2001" /><ref name="Thornton 2000" /> Crewed submeribles have been built rated to full ocean depth and have dived to the deepest known points of all the oceans.<ref name="Technology specifications" /><ref name="BBC Molloy 2019" />

==Unmanned diving== thumb|ROV working on a subsea structure|alt=A work class remotely operated underwater vehicle working on a complex underwater installation using a manipulator arm. Autonomous underwater vehicles (AUVs) and remotely operated underwater vehicles (ROVs) can carry out some functions of divers. They can be deployed at greater depths and in more dangerous environments. An AUV is a robot which travels underwater without requiring real-time input from an operator. AUVs constitute part of a larger group of unmanned undersea systems, a classification that includes non-autonomous ROVs, which are controlled and powered from the surface by an operator/pilot via an umbilical or using wireless remote control. In military applications AUVs are often referred to as unmanned undersea vehicles (UUVs).<ref name="ROVCAT" /><ref name="AUV" />

==Diving environments== The diving environment can influence the feasibility of use of a diving mode; particularly the level of confinement, which may physically prevent a direct vertical ascent to the surface air. This is a more immediate problem with scuba, where the diver has a limited breathing gas supply. In open-water diving there is no restriction, while in penetration diving there is an impenetrable restriction.<ref name="AS2815.3-1992" /><ref name="Jablonski 2006" /><ref name="High risk" />

===Open-water diving=== {{main|Open-water diving}}

thumb|Marine scientist coordinates a blue water dive for 4 companions - each at the end of a rope tether and each rope kept taut by a weight and pulley system The open-water diving mode refers to diving in an open water environment, where the diver has unrestricted access - by way of a direct vertical ascent - to the breathable air of the atmosphere. Other environmental hazards may exist, which do not affect the classification. In some contexts it also implies that there is no decompression obligation hindering direct ascent. This is the default mode for recreational scuba diving.<ref name="AS2815.3-1992" /> Blue-water diving is open-water diving done in mid-water where the bottom is out of sight of the diver and there may be no fixed visual reference. The techniques of blue-water diving have been developed over the years to suit the conditions and address the hazards of an environment which is functionally bottomless, and has no fixed visible positional references.<ref name="Haddock and Heine" />

===Penetration diving=== thumb|Cave diving {{main|Penetration diving}}

Penetration diving, or overhead diving, is diving under a physical overhead of any kind, where for a significant part of the dive it is not possible to ascend vertically to a free breathable air surface. Cave diving, wreck diving, ice diving and diving inside or under other natural or artificial underwater structures or enclosures are examples. The restriction on direct ascent increases the risk of diving under an overhead, and this is usually addressed by adaptations of procedures and use of equipment such as redundant breathing gas sources and guide lines to indicate the route to open water.<ref name="High risk" /><ref name="CoP Scientific" /><ref name="Jablonski 2006" />

Surface supplied breathing gas via umbilical both reduces the risk of running out of breathing gas, and of getting lost under an overhead obstruction, as the gas supply umbilical or airline can be followed out to the entrance point, but it does increase the risk of entrapment by snagging on the environment. An underwater tending point may be required at the entrance to the enclosed space. The available and manageable length of the umbilical is an absolute limitation on penetration.<ref name="Cal DIR" /><ref name="IMCA D022 2016" />

==Selection of a diving mode== {{see also|List of legislation regulating underwater diving|Diving safety}} The choice of diving mode for a given dive plan can be influenced by several factors. In recreational diving the main constraints are that the diver is competent to use the mode, that the mode is suited to the planned dive, and that the equipment and logistics are available.<ref name="Jablonski 2006" /> These constraints also apply to professional diving, but considerations of occupational safety, organisational procedural requirements, and legal constraints are added.<ref name="IMCA D014" /><ref name="Hong Kong" /><ref name="USNDM R6" />

==See also== * {{annotated link|Code of practice}} * {{annotated link|Diver certification}} * {{annotated link|Diver training}} * {{annotated link|Diver training standard}} * {{annotated link|Diving hazards}} * {{annotated link|Diving regulations}} * {{annotated link|Diving safety}} * {{annotated Link|Operations manual}} * {{annotated link|Professional diving}}

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<ref name="BBC Molloy 2019" >{{Cite news |url=https://www.bbc.com/news/science-environment-49636756 |title=US adventurer reaches deepest points in all oceans |last=Amos |first=Jonathan |work=BBC News |date=9 September 2019 |access-date=2019-09-10 |archive-date=28 June 2023 |archive-url=https://web.archive.org/web/20230628145122/https://www.bbc.com/news/science-environment-49636756 |url-status=live }}</ref>

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<ref name="Cal DIR" >{{cite web |url=https://www.dir.ca.gov/title8/6056.html |title=Subchapter 7. General Industry Safety Orders, Group 26. Diving Operations, Article 152. Diving Operations, §6056. Basic Operation Procedures. |website=www.dir.ca.gov |access-date=24 September 2025 }}</ref>

<ref name="CoP Inshore">{{cite book | title = Code of Practice Inshore Diving | author =  | publisher = The South African Department of Labour | location = Pretoria | url = http://www.labour.gov.za/DOL/downloads/documents/useful-documents/occupational-health-and-safety/inshorediving2014.pdf | access-date = 9 November 2016 | archive-date = 9 November 2016 | archive-url = https://web.archive.org/web/20161109161003/http://www.labour.gov.za/DOL/downloads/documents/useful-documents/occupational-health-and-safety/inshorediving2014.pdf | url-status = dead }}</ref>

<ref name="CoP Scientific">{{cite book |title=Code of Practice for Scientific Diving |author= |publisher=The South African Department of Labour |location=Pretoria |url=http://www.labour.gov.za/DOL/downloads/documents/useful-documents/occupational-health-and-safety/scientificdiving2014.pdf |access-date=9 November 2016 |archive-date=9 November 2016 |archive-url=https://web.archive.org/web/20161109155455/http://www.labour.gov.za/DOL/downloads/documents/useful-documents/occupational-health-and-safety/scientificdiving2014.pdf |url-status=dead }}</ref>

<ref name="Diving at Work Regulations 1997" >{{cite web |url=http://www.legislation.gov.uk/uksi/1997/2776/made |title=The Diving at Work Regulations 1997 |last=Staff |year=1977 |work=Statutory Instruments 1997 No. 2776 Health and Safety |publisher=Her Majesty's Stationery Office (HMSO) |location=Kew, Richmond, Surrey |access-date=6 November 2016}}</ref>

<ref name="Desco Helium">{{cite web|url=http://www.divedesco.com/P/189/USNavyHeliumHelmetwSingleExhaustValveearlyversion|title=DESCO 29019 Mark V Diving Helmet - Navy Helium Helmet with Single Exhaust Valve (early version) |last= |access-date=15 February 2018 |archive-date=16 February 2018 |archive-url=https://web.archive.org/web/20180216030158/http://www.divedesco.com/P/189/USNavyHeliumHelmetwSingleExhaustValveearlyversion |url-status=live }}</ref>

<ref name="DH Divex" >{{cite web |url=https://www.divingheritage.com/divexkern.htm |title=Divex |website=www.divingheritage.com |access-date=21 October 2024 }}</ref>

<ref name="Diving heritage Deep">{{cite web |url=http://www.divingheritage.com/goingdeep.htm |title=Going deep |website=www.divingheritage.com |access-date=2 July 2019 |archive-date=4 May 2019 |archive-url=https://web.archive.org/web/20190504155048/http://www.divingheritage.com/goingdeep.htm |url-status=live }}</ref>

<ref name="Doolette and Mitchell 2013" >{{cite journal |last1=Doolette |first1= David J. |last2=Mitchell |first2=Simon J. |title=Recreational technical diving part 2: decompression from deep technical dives. |journal=Diving and Hyperbaric Medicine |date=June 2013 |volume=43 |issue=2 |pages=96–104 |pmid= 23813463 }}</ref>

<ref name="Eleftheriou 2013">{{cite book |chapter=Chapter 4. Diving |last=Munro |first=Colin |year=2013 |title=Methods for the Study of Marine Benthos |edition=4th |editor-last=Eleftheriou | editor-first=Anastasios |publisher=John Wiley & Sons |location=Chichester |pages=125–127 |doi=10.1002/9781118542392.ch4 | isbn=978-1-118-54237-8}}</ref>

<ref name="FAO Hookah" >{{cite book |url=https://www.fao.org/documents/card/en?details=cc3789en |title=A practical guide on safe hookah diving |date=2023 |first1=Giampaolo |last1=Buonfiglio |first2=Alessandro |last2=Lovatelli |publisher=Food and Agriculture Organization of the United Nations |location=Rome |isbn=978-92-5-137476-4 |access-date=2023-09-20 |archive-date=2023-09-29 |archive-url=https://web.archive.org/web/20230929202852/https://www.fao.org/documents/card/en?details=cc3789en |url-status=live }}</ref>

<ref name="Fogarty 2020" >{{cite web |url=https://indepthmag.com/playing-with-fire-hydrogen-as-a-diving-gas/ |title=Playing with Fire: Hydrogen as a Diving Gas |first=Reilly |last=Fogarty |website=indepthmag.com/ |publisher=InDepth Magazine |date=4 March 2020 |access-date=6 January 2025 }}</ref>

<ref name="Gibb" >{{cite web |url=https://www.liveabout.com/every-dive-is-a-decompression-dive-2962937 |title=Every Dive Is a Decompression Dive |first=Natalie |last=Gibb |date=24 May 2019 |website=liveabout.com |access-date=29 October 2025 }}</ref>

<ref name="Haddock and Heine">{{cite book |title=Scientific Blue-Water Diving |last1=Haddock |first1=Stephen H.D. |last2=Heine |first2=John N. |publisher=California Sea Grant College Program |date=2005 |url=http://nsgd.gso.uri.edu/casg/casgh05001.pdf |access-date=23 November 2018 |archive-url=https://web.archive.org/web/20160325232044/http://nsgd.gso.uri.edu/casg/casgh05001.pdf |archive-date=25 March 2016 |url-status=dead |df=dmy-all }}</ref>

<ref name="Hockey">{{cite web | title = Hockey | author =  | work = History of Underwater Sports | publisher = World Underwater Federation (CMAS) | url = http://history.cmas.org/hockey-121122133950 | access-date = 9 November 2016 | archive-date = 8 June 2019 | archive-url = https://web.archive.org/web/20190608192217/http://history.cmas.org/hockey-121122133950 | url-status = dead }}</ref>

<ref name="High risk">{{cite book |title=Diving in High-Risk Environments |edition=4th |last=Barsky |first=Steven |year=2007 |publisher=Hammerhead Press |location=Ventura, California |isbn=978-0-9674305-7-7 }}</ref>

<ref name="Hong Kong" >{{cite web|url=https://www.labour.gov.hk/eng/public/os/B/diving.pdf |title=Code of Practice: Safety and Health at Work for Industrial Diving |publisher=Occupational Safety and Health Branch, Labour Department |location=Honk Kong |date=January 1998 }}</ref>

<ref name="Huffington 2014">{{cite web | title = SNUBA Is Basically Like Scuba Diving Or Snorkeling, But Easier | last = Ledbetter | first = Carly | website = The Huffington Post | publisher = The HuffingtonPost.com | url = http://www.huffingtonpost.com/2014/10/20/snuba-adventure_n_5983792.html | date = 22 October 2014 | access-date = 3 November 2016 | archive-date = 4 November 2016 | archive-url = https://web.archive.org/web/20161104075653/http://www.huffingtonpost.com/2014/10/20/snuba-adventure_n_5983792.html | url-status = live }}</ref>

<ref name="IDSA">{{cite web |url=http://www.idsaworldwide.org/docs/diverts0909.pdf |title=International Diver Training Certification: Diver Training Standards, Revision 4 |last= |date=29 October 2009 |work=Diver Training Standards |publisher=International Diving Schools Association |access-date=6 November 2016 |location=Malestroit, Brittany |url-status=dead |archive-url=https://web.archive.org/web/20160303215439/http://www.idsaworldwide.org/docs/diverts0909.pdf |archive-date=3 March 2016 }}</ref>

<ref name="Imbert 2006">{{cite journal | title = Commercial Diving: 90m Operational Aspects | last = Imbert | first = Jean Pierre | editor1-last = Lang | editor1-first = Michael A | editor2-last = Smith | editor2-first = N Eugene | journal = Advanced Scientific Diving Workshop | publisher = Smithsonian Institution | location = Washington, DC | date = February 2006 | url = http://www.plongeesout.com/articles%20publication/decompression/imbert/imbert%2090m.pdf | access-date = 30 June 2012 | archive-date = 24 September 2015 | archive-url = https://web.archive.org/web/20150924074411/http://www.plongeesout.com/articles%20publication/decompression/imbert/imbert%2090m.pdf | url-status = live }}</ref>

<ref name="IMCA D014">{{cite book| title = IMCA International Code of Practice for Offshore Diving: IMCA D 014 Rev. 2 | author =  | publisher = International Marine Contractor's Association | location = London | date = February 2014}}</ref>

<ref name="IMCA D022 2016" >{{cite book |last=|title=Guidance for diving supervisors IMCA D 022 |edition=Revision 1 |date=August 2016 |publisher=International Marine Contractors Association |location=London, UK |pages=10{{hyphen}}6 |chapter=10 - General diving procedures. Section 10.3 - Divers umbilicals }}</ref>

<ref name="Into the Blue">{{cite episode| title = Oceans: Into the Blue | series = Human Planet | series-link = Human Planet | number = 1 | publisher = British Broadcasting Corporation | station = BBC One | date = 13 January 2011 }}</ref>

<ref name="Jablonski 2006">{{cite book |chapter=9: Diving environments |last=Jablonski |first=Jarrod |year=2006 |title=Doing It Right: The Fundamentals of Better Diving |publisher=Global Underwater Explorers |location=High Springs, Florida |pages=137 |isbn=978-0-9713267-0-5 }}</ref>

<ref name="Lee et al 2020" >{{cite journal |last1=Lee |first1=D.W. |last2=Jung |first2=S.J. |last3=Ju |first3=J.S. |title=The effects of heliox non-saturation diving on the cardiovascular system and cognitive functions. |journal=Undersea Hyperb Med |date=First Quarter 2020 |volume=47 |issue=1 |pages=93–100 |doi=10.22462/01.03.2020.10 |pmid=32176950 }}</ref>

<ref name="Loudoun" >{{cite web |url=http://www.thepressureproject.com.au/history-of-breath-holding-and-freediving-by-carrie-loudoun/ |title=History of Breath Holding and Freediving |first=Carrie |last=Loudoun |website=www.thepressureproject.com.au |access-date=30 October 2025 }}</ref>

<ref name="Mitchell et al 2012" >{{cite journal |author1=Mitchell, Simon J |author-link=Simon Mitchell |author2=Bennett, Michael H |author3=Bird, Nick |author4=Doolette, David J |author5=Hobbs, Gene W |author5-link=Gene Hobbs |author6=Kay, Edward |author7=Moon, Richard E |author8=Neuman, Tom S |author9=Vann, Richard D |author10=Walker, Richard |author11=Wyatt, HA |title=Recommendations for rescue of a submerged unresponsive compressed-gas diver |journal=Undersea & Hyperbaric Medicine |volume=39 |issue=6 |pages=1099–108 |year=2012 |pmid=23342767 }}</ref>

<ref name="mixed gas and oxygen" >{{cite book |title=The NOAA Diving Manual: Diving for Science and Technology |chapter-url=https://books.google.com/books?id=dWI8e8rVbJ0C&q=helium+%28He%29+is+the+other+inert+gas+commonly+used+in+breathing+mixtures+for+divers |access-date=8 March 2016 |edition=illustrated |year=1992 |publisher=DIANE Publishing |isbn=978-1-56806-231-0 |pages=15.1 |chapter=15: Mixed gas and oxygen diving }}</ref>

<ref name=NPAL>{{cite report| title = North Pacific Acoustic Laboratory: Environmental Impact Statement | year = 2001 | publisher = Office of Naval Research | location = Arlington, Virginia | pages = 3–45 | volume = 1 | url = https://books.google.com/books?id=fKo4AQAAMAAJ&pg=SA3-PA45}}</ref>

<ref name="P D Handbook 5.3" >{{cite book |editor-last=Bevan |editor-first=John |title=The Professional Divers's Handbook |edition=second |year=2005 |publisher=Submex Ltd. |location=Gosport, Hampshire |isbn= 978-0950824260 |page=238 |chapter=Section 5.3 }}</ref>

<ref name="Rekdal 2004">{{cite web | title = Guidelines to activity report for diving operations on the Norwegian continental shelf | last = Rekdal | first = Ole | year = 2004 | publisher = Petroleum Safety Authority | url = http://www.psa.no/getfile.php/z%20Konvertert/Products%20and%20services/Forms/Dokumenter/rapporteringavbemmanedeundervannsoperasjonere.doc | format = DOC | access-date = 3 November 2016 | archive-url = https://web.archive.org/web/20170109045535/http://www.psa.no/getfile.php/z%20Konvertert/Products%20and%20services/Forms/Dokumenter/rapporteringavbemmanedeundervannsoperasjonere.doc | archive-date = 9 January 2017 | url-status = dead }}</ref>

<ref name="Rigging stage bottles" >{{cite web |url=https://www.tdisdi.com/sdi-diver-news/rigging-stage-bottles-how-to-carry-extra-scuba-tanks-and-why/ |title=Rigging Stage Bottles… How to carry extra scuba tanks… and why. |website=www.tdisdi.com |date=17 June 2011 |access-date=15 June 2023 |archive-date=6 April 2023 |archive-url=https://web.archive.org/web/20230406050517/https://www.tdisdi.com/sdi-diver-news/rigging-stage-bottles-how-to-carry-extra-scuba-tanks-and-why/ |url-status=live }}</ref>

<ref name="Risberg et al 2023" >{{cite journal|last1=Risberg |first1=J. |last2=van Ooij |first2=P.J. |last3=Eftedal |first3=O.S. |title=Decompression procedures for transfer under pressure ('TUP') diving. |journal=Diving Hyperb Med |date=30 September 2023 |volume=53 |issue=3 |pages=189–202 |doi=10.28920/dhm53.3.189-202 |pmid=37718292 |pmc=10597602 }}</ref>

<ref name="ROVCAT">{{cite web |title=ROV Categories – Summary |author = |work=ROVs |publisher=Marine Technology Society |url=http://www.rov.org/rov_categories.cfm |access-date=16 September 2016 |archive-url=https://web.archive.org/web/20160917162517/http://www.rov.org/rov_categories.cfm |archive-date=17 September 2016 |url-status=dead |df=dmy-all}}</ref>

<ref name="Rugby">{{cite web | title = Rugby | last = Wiesner | first = Rudi | work = History of Underwater Sports | publisher = World Underwater Federation (CMAS) | url = http://history.cmas.org/rugby | access-date = 9 November 2016 | archive-url = https://web.archive.org/web/20130930041012/http://history.cmas.org/rugby | archive-date = 30 September 2013 | url-status = dead }}</ref>

<ref name="seattle1995" >{{cite news |url=https://archive.seattletimes.com/archive/19950122/2100660/snuba-diving-offers-a-chance-to-experience-rapture-of-the-shallows |title=Snuba Diving Offers A Chance To Experience Rapture Of The Shallows |last=Jackson |first=Kristin |date=1995-01-22 |work=Seattle Times |publisher=Seattle Times Company |access-date=2016-09-27 |archive-date=2012-09-22 |archive-url=https://web.archive.org/web/20120922085608/http://community.seattletimes.nwsource.com/archive/?date=19950122&slug=2100660 |url-status=live }}</ref>

<ref name="scubadoc hookah" >{{cite web |url=https://www.scubadoctor.com.au/intro-to-hookah-diving.htm |website=The Scuba Doctor |title=Hookah Diving |access-date=9 January 2024 |archive-date=13 November 2023 |archive-url=https://web.archive.org/web/20231113200231/https://www.scubadoctor.com.au/intro-to-hookah-diving.htm |url-status=live }}</ref>

<ref name="snuba">{{cite web| title = Lifestyle: SNUBA and the Tourism Industry | author =  | publisher = SNUBA International | url = http://www.snuba.com/wp-content/uploads/2012/03/Lifestyle_Guide-to-Licensing-SRC_email.pdf | url-status = dead | archive-url = https://web.archive.org/web/20170109045402/http://www.snuba.com/wp-content/uploads/2012/03/Lifestyle_Guide-to-Licensing-SRC_email.pdf | date = 2012 | access-date = 28 September 2016 | archive-date = 9 January 2017}}</ref>

<ref name="Spearfishing">{{cite web | title = Spearfishing | author =  | work = History of Underwater Sports | publisher = World Underwater Federation (CMAS) | url = http://history.cmas.org/spearfishing | access-date = 9 November 2016 | archive-date = 8 June 2019 | archive-url = https://web.archive.org/web/20190608192821/http://history.cmas.org/spearfishing | url-status = dead }}</ref>

<ref name="subsea 2001">{{cite news | title = Subsea Technology: Atmospheric diving suits bridge gap between saturation diving and ROV units | last1 = Thornton | first1 = Mike | last2 = Randall | first2 = Robert E. | last3 = Albaugh | first3 = E. Kurt | magazine = Offshore Magazine | location = Tulsa, Oklahoma | url = http://www.offshore-mag.com/articles/print/volume-61/issue-1/news/subsea-technology-atmospheric-diving-suits-bridge-gap-between-saturation-diving-and-rov-units.html | date = 1 January 2001 | access-date = 24 September 2016 | archive-date = 24 September 2016 | archive-url = https://web.archive.org/web/20160924184324/http://www.offshore-mag.com/articles/print/volume-61/issue-1/news/subsea-technology-atmospheric-diving-suits-bridge-gap-between-saturation-diving-and-rov-units.html | url-status = live }}</ref>

<ref name=TDISDI >{{cite web|url=https://www.tdisdi.com/tdi-diver-news/making-every-breath-count-again-and-again/ |title=Making Every Breath Count… Again and Again! |date=26 September 2011 |access-date=23 September 2025 |website=www.tdisdi.com }}</ref>

<ref name="Technology specifications" >{{cite web |url=https://fivedeeps.com/home/technology/sub/ |title=Triton 36000/2: Full Ocean Depth |website=fivedeeps.com |access-date=2023-01-16 |archive-date=14 May 2019 |archive-url=https://web.archive.org/web/20190514014338/https://fivedeeps.com/home/technology/sub/ |url-status=live }}</ref>

<ref name="Thornton 2000">{{cite book |title=A Survey and Engineering design of atmospheric diving suits |last=Thornton |first=Michael Albert |publisher=((Calhoun: The NPS Institutional Archive)) |location=Monterey, California |url=http://calhoun.nps.edu/bitstream/handle/10945/7802/surveyengineerin00thor.pdf?sequence=1 |date=1 December 2000 | access-date=28 September 2016 |archive-date=2 October 2016 | archive-url=https://web.archive.org/web/20161002032316/http://calhoun.nps.edu/bitstream/handle/10945/7802/surveyengineerin00thor.pdf?sequence=1 |url-status=live }}</ref>

<ref name="USNDM R6" >{{cite book |title=US Navy Diving Manual, 6th revision |year=2006 |publisher=US Naval Sea Systems Command |location=United States |url=http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9 |author=US Navy |ref={{sfnRef|US Navy Diving Manual Revision 6}} |access-date=16 March 2016 |archive-date=2 May 2008 |archive-url=https://web.archive.org/web/20080502023541/http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageId=3.9 |url-status=dead }}</ref>

<ref name="UW360" >{{cite web |url=https://www.uw360.asia/the-evolution-of-freediving/ |title=The Evolution of Freediving |date=11 April 2019 |website=www.uw360.asia |access-date=30 October 2025 }}</ref>

</references>

===Sources=== # {{cite book| title = US Navy Diving Manual, 6th revision | author =  | year = 2006 | publisher = US Naval Sea Systems Command | location = Washington, DC. | url = http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9 | ref = {{sfnRef|US Navy Diving Manual|2006}}}} # {{cite book | title = NOAA Diving Manual, Diving for Science and Technology | edition = 4th | author =  | editor-last = Joiner | editor-first = James T | publisher = National Oceanic and Atmospheric Administration, Office of Oceanic and Atmospheric Research, National Undersea Research Program | location = Silver Spring, Maryland | date = 28 February 2001 | isbn = 978-0-941332-70-5 | ref = {{sfnRef|NOAA Diving Manual|2001}} | url = https://archive.org/details/noaadivingmanual00noaa }} CD-ROM prepared and distributed by the National Technical Information Service (NTIS) in partnership with NOAA and Best Publishing Company

Category:Underwater diving modes