thumb|right|A cave diver running a reel with guide line into the overhead environment
Cave diving is underwater diving in water-filled caves. It may be done as an extreme sport, a way of exploring flooded caves for scientific investigation, or for the search for and recovery of divers or, as in the 2018 Thai cave rescue, other cave users. The equipment used varies depending on the circumstances, and ranges from breath hold to surface supplied, but almost all cave-diving is done using scuba equipment, often in specialised configurations with redundancies such as sidemount or backmounted twinset. Recreational cave-diving is generally considered to be a type of technical diving due to the lack of a free surface during large parts of the dive, and often involves planned decompression stops. A distinction is made by recreational diver training agencies between cave-diving and cavern-diving, where cavern diving is deemed to be diving in those parts of a cave where the exit to open water can be seen by natural light. An arbitrary distance limit to the open water surface may also be specified.
Cavern
Cavern diving is an arbitrarily defined, limited scope activity of diving in the naturally illuminated part of underwater caves, where the risk of getting lost is small, as the exit can be seen, and the equipment needed is reduced due to the limited distance to surface air. It is defined as a recreational diving activity as opposed to a technical diving activity on the grounds of low risk and basic equipment requirements.
As most cave-diving is done in an environment where there is no free surface with breathable air allowing an above-water exit, it is critically important to be able to find the way out before the breathing gas runs out. This is ensured by the use of a continuous guideline between the dive team and a point outside of the flooded part of the cave, and diligent planning and monitoring of gas supplies. Two basic types of guideline are used: permanent lines, and temporary lines. Permanent lines may include a main line starting near the entrance/exit, and side lines or branch lines, and are marked to indicate the direction along the line to the nearest exit. Temporary lines include exploration lines and jump lines. In some caves, changes of depth of the cave along the dive route will constrain decompression depths, and gas mixtures and decompression schedules can be tailored to take this into account.
Skills
thumb|right|Warning sign near the entrance to a cave|alt=A white warning sign with a picture of the Grim Reaper and the headline "Prevent your death. Go no farther" over black text explaining the dangers to divers of proceeding into the cave without proper equipment and certification.Most open-water diving skills apply to cave-diving, and there are additional skills specific to the environment, and to the chosen equipment configuration.
- Good buoyancy control, trim and finning technique help preserve visibility in areas with silt deposits. The ability to reverse kick to back out of restrictions where there is no space to turn around is useful.
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| Cave diver<br />(Zone 2)
| Cave diver II
| Cave Diver Level 1
| Cave Diver, Level 1
| Intro to Cave Diving
| Cave Diver Level I
| Basic/Intro Cave Diver
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|Intro to Cave
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|Cave Diver Level 2
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| Apprentice to Cave
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| Apprentice Cave Diver
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| Cave diver<br />(Zone 3)
| Cave diver III
| Cave Diver Level 2
| Cave Diver, Level 3 and Cave Explorer, Level 4
| Full Cave Diver
| Cave Diver Level II
| Cave Diver
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|Full Cave
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| Cave diver<br />(58 m)
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| Cave 2 + TEK 1
| Cave Explorer Level 5
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| Cave diver guide
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| Cave Guide (Technical Support Leader)
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| Cave diving instructor 1
| Cave diving instructor I
| Cave Instructor Level 1
| Assistant Instructor (ASI)
| Cavern Instructor
| Assistant Instructor
| Instructor
| Specialty Instructor
Diver propulsion vehicles, or scooters, are sometimes used to extend the range by reducing the work load on the diver and allowing faster travel in open sections of cave. Reliability of the diver propulsion vehicle is very important, as a failure could compromise the ability of the diver to exit the cave before running out of gas. Where this is a significant risk, divers may tow a spare scooter.
Dive lights are critical safety equipment, as it is dark inside caves. Each diver generally carries a primary light, and at least one backup light. A minimum of three lights is recommended. The previous record of was held by Frédéric Swierczynski, and before that by Xavier Méniscus at , on 30 December 2019, both also at Font Estramar cave. Before that, Nuno Gomes had descended to at Boesmansgat in South Africa.
UK history
thumb|Cave-diving equipment from 1935 in the museum at [[Wookey Hole Caves]]
The Cave Diving Group (CDG) was established informally in the United Kingdom in 1935 to organise training and equipment for the exploration of flooded caves in the Mendip Hills of Somerset. The first dive was made by Jack Sheppard on 4 October 1936,
Sources
- "Skin Diver Killed in Submerged Cave", The New York Times, 16 May 1955, Page 47.
- Basic Cave Diving: A Blueprint for Survival, Sheck Exley 1977.
External links
- Atlas of Caves Worldwide caveatlas.com
- Florida Cave & Cavern List
- History article Cave Diving Group, UK, 28 March 2010
- Woodville Karst Plain Project non profit organization about North Florida's underwater cave systems
- Wakulla system Todd Kincaid, University of Wyoming
- Global Underwater Explorers non profit organization in Florida, education and exploration; Project Baseline, online spatial database of global underwater conditions
- International Underwater Cave Rescue and Recovery (IUCRR) International non profit organization registered in Florida
- Cave Diving Down Under (Australia) social media site for cave diving in Australia
- Dominican Republic Speleological Society