Cave diving

diving hazards

. Cave diving is a form of penetration diving, meaning that in an emergency a diver cannot ascend directly to the surface due to the cave's ceilings, and instead may have to swim horizontally. The underwater navigation through the cave system may be difficult and exit routes may be at considerable distance, requiring the diver to have sufficient breathing gas to make the journey, resulting in potential deep diving risks.

Visibility can be low, or non-existent. While a less-intensive kind of diving called cavern diving does not take divers beyond the outermost part of the cave reached by natural light, true cave diving can involve penetrations of many thousands of feet, well beyond the reach of sunlight. The level of darkness experienced creates an environment impossible to see in without an artificial form of light. Caves often contain sand, mud, clay, silt, or other sediment that can further reduce underwater visibility in seconds when stirred up.

Caves can carry strong water currents. Most caves emerge on the surface as either springs or siphons. Springs have out flowing currents, where water is coming up out of the Earth and flowing out across the land's surface. Siphons have inflowing currents where, for example, an above-ground river is going underground. Some caves are complex and have some tunnels with out-flowing currents, and other tunnels with inflowing currents. If currents are not properly managed, they can cause serious problems for the diver.

Cave diving is perceived as one of the more dangerous sports in the world. This perception is arguable because the vast majority of divers who have lost their lives in caves have either not undergone specialized training or have had inadequate equipment for the environment. Many cave divers have suggested that cave diving is in fact statistically much safer than recreational diving due to the much larger barriers imposed by experience, training, and equipment cost.

There is no reliable worldwide database listing all cave diving fatalities. Such fractional statistics as are available, however, suggest that very few divers have ever died while following accepted protocols and while using equipment configurations recognized as acceptable by the cave diving community. In the very rare cases of exceptions to this rule there have always been unusual circumstances.

Safety

Most cave divers recognize five general rules or contributing factors for safe cave diving, which were popularized, adapted and became generally accepted from Sheck Exley's 1977 publication Basic Cave Diving: A Blueprint for Survival. In this book, Exley included accounts of actual cave diving accidents, and followed each one with a breakdown of what factors contributed to the accident. Despite the uniqueness of any individual accident, Exley found that at least one of a small number of major factors contributed to each one. This technique for breaking down accident reports and finding common causes among them is now called Accident Analysis, and is taught in introductory cave diving courses. Exley outlined a number of these resulting cave diving rules, but today these five are the most recognized:

• Training: A safe cave diver never exceeds the boundaries of his/her training. Cave diving is normally taught in segments, each segment focusing on more complex aspects of cave diving. Furthermore, each segment of training must be coupled with real world experience before moving to a more advanced level. Accident analysis of recent cave diving fatalities has proven that academic training without sufficient real world experience is not enough should an emergency occur underwater. Only by slowly building experience can one remain calm enough to recall their training should a situation arise, whereas an inexperienced diver (who may be recently trained) —will tend to panic when confronted with a similar situation.

A cave diver running a reel with guide line into the overhead environment

• Guide line: A continuous guide line is maintained at all times between the leader of a dive team and a fixed point selected outside the cave entrance in open water. Often this line is tied off a second time as a backup directly inside the cavern zone. As the dive leader lays the guideline he takes great care to ensure there is sufficient tension on the line. Should a silt out occur, divers can find the taut line and successfully follow it back to the cave entrance. It is important to note that not using a guide line is the number one cause of fatality among untrained, non-certified divers who venture into caves.

• Depth rules: Gas consumption and decompression obligation increase with depth, and it is critical that no cave diver exceeds the dive plan or the maximum operating depth (MOD) of the gas mixture used. Also, the effects of nitrogen narcosis are possibly greater in a cave, even for a diver who has the same depth experience in open water. Cave divers are advised not to dive to "excessive depth," and to keep in mind this effective difference between open water depth and cave depth. It should be noted that among fully trained cave divers, not paying sufficient attention to depth is the number one cause of fatality.

• Air (gas) management: The most common protocol is the 'rule of thirds,' in which one third of the initial gas supply is used for ingress, one third for egress, and one third to support another team member in the case of an emergency. UK practice is to adhere to the rule of thirds too, but with added emphasis that you must keep depletion of your separate air systems "balanced," so that the loss of a complete air system will still leave you with sufficient air to return safely. Note that the rule of thirds makes no allowance for the increased air consumption that the loss of an air system will induce. Dissimilar tank sizes among the divers are also not included and the proper amount of air reserve must be calculated for each dive (if tanks are dissimilar). UK practice is to assume that anyone else diving with you does not exist, as in a typical UK sump there is absolutely nothing that you can do to assist him/her. Most UK cave divers dive solo. US sump divers follow a similar protocol. Note that the rule of thirds was devised as an approach to diving Florida's caves - they typically have high outflow currents, which help to reduce air consumption when exiting. In a cave system with little (or no) outflow it is mandatory to reserve more air than is dictated by the rule of thirds.

• Lights: All cave divers must have three independent sources of light. One is considered the primary and the other two are considered backup lights. If ANY ONE of the three light sources fail for one diver, the dive is called off and ended for all members of the dive team.

These five rules may be remembered with the mnemonic The Good Divers Are Living, the first letter of each word referring to the first letter of the corresponding rule. An alternative mnemonic taught in the United States is Thank Goodness All Divers Live, requiring a rearrangement of the rules.

In recent years new contributing factors are considered after reviewing accidents which indicate solo diving, diving with incapable dive partners, video or photography in caves, complex cave dives and cave diving in large groups. With the establishment of technical diving the usage of mixed gases such as trimix for bottom gas, nitrox and oxygen for decompression the margin for error increases. Accident analysis informs us that breathing the wrong gas at the wrong depth and or not analyzing the breathing gas properly may lead to cave diving accidents.

Cave diving requires a wide variety of very specialized techniques. Divers who do not adhere strictly to these techniques, as well as equipment specifications, greatly increase the amount of risk against them. The cave diving community works hard to educate the public on the risks they assume when they enter water-filled caves. Warning signs with the likenesses of the Grim Reaper have been placed just inside the openings of many popular caves in the US, and others have been placed in nearby parking lots and local dive shops.

Many cave diving sites around the world contain basins, which are also popular open-water diving sites. These sites try to minimize the risk of untrained divers being tempted to venture inside the cave systems. With the support of the cave diving community, many of these sites enforce a "no-lights rule" for divers who lack cave training — they may not carry any lights into the water with them. It is easy to venture into an underwater cave with a light and not realize how far away from the entrance (and daylight) one has swum; this rule is based on the theory that, without a light, divers will not venture beyond the point where they can see.

Training

Cave diving training includes equipment selection and configuration, guideline protocols and techniques, gas management protocols, communication techniques, propulsion techniques, emergency management protocols, and psychological education. As cave diver training stresses the importance of safety it does point out cave conservation ethics as well. Most training programs contain various stages of certification and education.

• Cavern training explains the basic skills needed to enter into the overhead environment. Training will generally consist of gas planning, propulsion techniques needed to deal with the silty environments in many caves, reel and handling, and communication. Once certified as a cavern diver, a diver may undertake cavern diving with a cavern (or greater) certified "buddy," as well as advance into cave diving training.

• Introduction into cave training builds off of the techniques learned during cavern training and includes the training needed to penetrate beyond the cavern zone and working with permanent guidelines that exist in many caves. Once intro to cave certified, a diver may penetrate much further into a cave, usually limited by 1/3rd of a single cylinder, or in the case of a basic cave certification, 1/6th of double cylinders. An intro cave diver is usually not certified to do complex navigation.

• Apprentice cave training serves as the building block from intro to full certification and includes the training needed to penetrate deep into caves working from both permanent guide lines as well as limited exposure to side lines that exist in many caves. Training covers complex dive planning and decompression procedures used for longer dives. Once apprentice certified, a diver may penetrate much further into a cave, usually limited by 1/3rd of double cylinders. An apprentice diver is also allowed to do a single jump or gap (a break in the guideline from two sections of mainline or between mainline and sideline) during the dive. An apprentice diver typically has one year to finish full cave or must repeat the apprentice stage.

• Full cave training serves final level of basic training and includes the training needed to penetrate deep into the cave working from both permanent guidelines as well as sidelines and may plan and complete complex dives deep into a system using decompression to stay longer. Once cave certified, a diver may penetrate much further into a cave, usually limited by 1/3rd of double cylinders. A Cave diver is also allowed to do multiple jumps or gaps (a break in the guideline from two sections of mainline or between mainline and sideline) during the dive.

International differences

The cave diving community is a global one, partly due to the highly specialised nature with the resulting small numbers of practitioners at a local level.

However, cave diving practice can differ markedly by locality. One such difference is the use of a floating polypropylene guide line. Most cave divers in the U.S. balk at the use of any sort of floating guide line, 6 mm polypropylene line is the norm in UK precisely because it does float - the line is regularly anchored to stones, lead weights, or whatever is needed and the floating keeps it clear of mud and silt. In Europe, thinner yet slightly buoyant line is typical. Cave diving practices in some localities may be different than those in other parts of the world because those caves require specialized techniques. It is always recommended that individuals contact someone familiar with a cave before venturing inside a cave.

Regularity in signs and warnings may also differ around the world. For example, warnings signs are rare in the UK.

History

Jacques-Yves Cousteau, co-inventor of the first SCUBA equipment, was both the world's first SCUBA diver and the world's first SCUBA cave diver. However, many cave divers penetrated caves prior to the advent of SCUBA with surface supplied UBA through the use of umbilical hoses and compressors. SCUBA diving in all its forms, including cave diving, has advanced in earnest since he introduced the aqua-Lung in 1943.

UK history

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, using a home-made drysuit surface fed from a modified bicycle pump, which allowed Sheppard to pass Sump 1 of Swildon's Hole. Swildon's is an upstream feeder to the Wookey Hole resurgence system. The difficulty of access to the sump in Swildon's prompted operations to move to the resurgence, and the larger cave there allowed use of conventional "hard hat" equipment which was secured from the Siebe Gorman company. The left photograph on the standard diving dress page will give some indication of the scale of operations this entailed. In UK cave diving, the term "Sherpa" is used without a drop of irony for the people who carry the diver's gear, and before the development of SCUBA equipment such undertakings could be monumental operations.

Diving in the spacious third chamber of Wookey Hole led to a rapid series of advances, each of which was dignified by being given a successive number, until an air surface was reached at what is now known as "Chamber 9." Some of these dives were broadcast live on BBC radio, which must have been a quite surreal experience for both diver and audience.

Cave diving equipment in the museum at Wookey Hole Caves

The number of sites where standard diving dress could be used is clearly limited and there was little further progress before the outbreak of World War II reduced the caving community considerably. However, the rapid development of underwater warfare through the war made a lot of surplus equipment available. The CDG re-formed in 1946 and progress was rapid. Typical equipment at this time was a frogman rubber diving suit for insulation (water temperature in the UK is typically 4 °C), an oxygen diving cylinder, soda lime absorbent canister and counter-lung comprising a rebreather air system and an "AFLOLAUN," meaning "Apparatus For Laying Out Line And Underwater Navigation." The AFLOLAUN consisted of lights, line-reel, compass, notebook (for the survey), batteries, and more.

Progress was typically by "bottom walking", as this was considered less dangerous than swimming (note the absence of buoyancy controls). The use of oxygen put a depth limit on the dive, which was considerably mitigated by the extended dive duration. This was the normal diving equipment and methods until approximately 1960 when new techniques using wetsuits (which provide both insulation and buoyancy compensation), twin open-circuit SCUBA air systems, helmet-mounted lights and free-swimming with fins. The increasing capacity and pressure rating of air bottles also extended dive durations.

U.S. History

In the 1970s, cave diving greatly increased in popularity among divers in the United States. However, there were very few experienced cave divers and almost no formal classes to handle the surge in interest. The result was a large number of divers trying to cave dive without any formal training. This resulted in more than 100 fatalities over the course of the decade. The state of Florida came close to banning SCUBA diving around the cave entrances. The cave diving organizations responded to the problem by creating training programs and certifying instructors, in addition to other measures to try to prevent these fatalities. This included posting signs, adding no-lights rules, and other enforcements.

In the United States, Sheck Exley was a pioneering cave diver who first explored many Florida underwater cave systems, and many other underwater cave systems throughout the US and the world. On February 6, 1974, Exley was also the first chairman of the Cave Diving Section of the National Speleological Society.

Since the 1980s, prevention measures to reduce diver fatalities have been successful, and today it is rare for an untrained diver to die in an underwater cave, despite later surges in popularity in the 1980s and 1990s. The 1980s saw a few refinements to the equipment used for cave diving, most importantly better lights and smaller batteries. In the 1990s equipment configurations became a little more standard than they had been in the past, due mostly to the WKPP's adaptation and popularization of the Hogarthian Rig, a concept credited to Bill "Hogarth" Main which states not to take what you don't need, keep it simple and streamline.

Documentary films made by Wes Skiles and Jill Heinerth have contributed to the increasing popularity of cave diving in the early 21st century.

Many sites today have strict rules about diving within one's level of training and requiring proof of that level, more so than most recreational diving sites elsewhere in the country. Today, the cave community is most focused on training, exploration, public awareness, and cave conservation. Different organizations place different emphasis on these priorities.

Cave diving venues

Grand Bahama Island

The caves and caverns of Grand Bahama, contain an immense underwater cavern, with a vast, flooded, labyrinth of caverns, caves and submerged tunnels that honeycomb the entire island of Grand Bahama and the surrounding sea bed. The inland caves are not abundant with life, but do contain creatures living in the caves, other than the migrating Gray Snappers. Residents of these caves include a type of blind cave fish, and remipedia that don't pose any threat to cave divers.

The caves in the Bahamas were formed during the last ice age. With much of the earth's water held in the form of glacial ice, the sea level fell hundreds of feet, leaving most of the Bahama banks, which are now covered in water, high and dry. Rain falling on the most porous limestone, slowly filtered down to sea level forming a lens where it contacted the denser salt water of the ocean permeating the spongy lime stone. The water at the interface, was acidic enough to dissolve away the limestone and form the caves. Then, as more ice formed and the sea level dropped even further, the caves became dry and rainwater dripping through the ceiling, over thousands of years, created the incredible crystal forests of stalagmites which now decorate the caves. Finally, when the ice melted and the sea level rose, the caves were reclaimed by the sea.

Central and Northern Florida, U.S.

The largest and most active cave diving community in the United States is in north-central Florida. The North Floridan Aquifer expels groundwater through numerous first-magnitude springs, each providing an entrance to the aquifer's labyrinthine cave system. These high-flow springs have resulted in Florida cave divers developing special techniques for exploring them, since some have such strong currents that it is impossible to swim against them.

The longest known underwater cave system in the USA, The Leon Sinks cave system, near Tallahassee, Florida, has multiple interconnected sinks and springs spanning two counties (Leon & Wakulla). One main resurgence of the system, Wakulla Springs, is explored exclusively by a very successful and pioneering project called the Woodville Karst Plain Project (WKPP), although other individuals and groups like the US Deep Cave Diving Team, have explored portions of Wakulla Springs in the past.

The deepest known underwater cave in the USA is Weeki Wachee Spring. Due to its strong outflow, divers have had limited success penetrating this first magnitude spring until 2007, when drought conditions eased the outflowing water allowing team divers from Karst Underwater Research to penetrate to depths of 400 ft (120 m).

The Florida caves are formed from geologically young limestone with moderate porosity. The absence of speleothem decorations which can only form in air filled caves, indicates that the flooded Florida caves have a single genetic phase origin, having remained water filled even during past low sea levels. In plan form, the caves are relatively linear with a limited number of side passages allowing for most of the guidelines to be simple paths with few permanent tees. It is common practice for cave divers in Florida to joint a main line with a secondary line using a jump reel when exploring side passages, in order to maintain a continuous guideline to the surface.

Yucatan Peninsula, Mexico

While there is great potential for cave diving in the continental karst throughout Mexico, the vast majority of cave diving in Mexico occurs in the Yucatan Peninsula. While there are thousands of deep pit cenotes throughout the Yucatan Peninsula including in the states of Yucatan and Campeche, the extensive sub-horizontal flooded cave networks for which the peninsula is known are essentially limited to a 10 km wide strip of the Caribbean coastline in the state of Quintana Roo extending south from Cancun to the area of Tulum and the Sian Ka'an Biosphere Reserve, although some short segments of underwater cave have been explored on the north-west coast (Yucatan State).

In the Yucatan Peninsula, any surface openings where groundwater can be reached is called cenote, which is a Spanish form of the Maya word d'zonot. The cave systems formed as normal caves underwater, but upper sections drained becoming air filled during past low sea levels. During this vadose, or air filled state, abundant speleothem deposits formed. The caves and the vadose speleothem were subsequently reflooded and became hydraulically reactivated as rising sea levels also raised the water table. These caves are therefore polygenetic, having experienced more than one cycle of formation below the water table. Polygenetic coastal cave systems with underwater speleothem are globally common, with notable examples being on the Balearic Islands (Mallorca, Menorca) of Spain, the islands of the Bahamas, Bermuda, Cuba, and many more.

As with all cave speleothems, the underwater speleothems in the Yucatan Peninsula are fragile. If a diver accidentally breaks off a stalactite from the ceiling or other speleothem formation, it will not reform as long as the cave is underwater so active cave conservation diving techniques are paramount.

In plan form, the Quintana Roo caves are extremely complex with anastomotic interconnected passages. When cave diving through the caves, the pathways then appear to have many offshoots and junctions, requiring careful navigation with permanent tees or the implementation of jumps in the guideline.

The beginning of the 1980s brought the first cave divers from the U.S. to the Yucatan Peninsula, Quintana Roo (Q.Roo) to explore cenotes such as Carwash, Naharon and Maya Blue, but also to central Mexico where resurgence rivers such as Rio Mante, sinkholes such as Zacaton were documented.

In the Yucatan, the 1980s ended with the discoveries of the Dos Ojos and Nohoch Nah Chich cave systems which lead into a long ongoing competition of which exploration team had the longest underwater cave system in the world at the time, with both teams vying for first place.

The beginning of the 1990s led into the discovery of underwater caves such as Aereolito on the island of Cozumel, ultimately leading to the 5th biggest underwater cave in the world.

By the mid 1990s a push into the central Yucatan Peninsula by dedicated deep cave explorers discovered a large number of deep sinkholes, or pit cenotes, such as Sabak Ha, Utzil and deep caves such as Chacdzinikche, Dzibilchaltun, Karkirixche that have been explored and mapped. To this day these deep caves of the central Yucatan remain largely unexplored due to the sheer number of cenotes found in the State of Yucatan, as well as the depth involved that can be only tackled using technical diving techniques or rebreathers. In the end of the last millennium closed circuit rebreather (CCR) cave diving techniques where employed in order to explore these deep water filled caves.

By the end of the 1990s, The Pit in the Dos Ojos cave system located 5.8 km from the Caribbean coast in the state of Quintana Roo had been discovered, and it is presently (2008) 119 m deep. At that time, technical diving and rebreather equipment and techniques became common place.

By the turn of the millennium the longest underwater cave system, called Ox Bel Ha was established by cave diving explorers whose combined efforts and information helped join segments of previously explored caves. The use of hand held GPS technology and aerial and satellite images for reconnaissance during exploration became common. New technology such as rebreathers and diver propulsion vehicles (DPVs) became available and where utilized for longer penetration dives. As of January 2008, Ox Bel Ha includes 170 km of underwater passage (See QRSS for current statistics).

Active exploration continues in the new millennium. Most cave diving exploration is now conducted on the basis of "mini projects" lasting 1 – 7 days, and occurring many times a year, and these may include daily commutes from home to jungle dive base camps located within 1 hour from road access.

In 2006 and 2007 a number of large previously explored and mapped cave systems have been connected utilizing sidemount cave diving techniques and many times no-mount cave diving techniques in order to pass through these tight cave passages, creating the second largest connected underwater cave systems on the planet, Sac Actun, which presently has a length extent of 155 km (See QRSS for current statistics).

Many cave maps have been published by the Quintana Roo Speleological Survey (QRSS).

United Kingdom

UK requirements are generally that all people wishing to take up cave diving must be competent cavers before they start cave diving. This is primarily because most British cave dives are at the far end of dry caves. There are individuals that begin cave diving directly from the recreational diving, but they represent a minority in the UK, and represent only a few percent of the Cave Diving Group (CDG).

Australian cave diving and the CDAA

Australia has many spectacular water filled caves and sinkholes, but unlike the UK, most Australian cave divers come from a general ocean-diving background. The "air-clear" water of the sinkholes and caves can be found in the Mount Gambier area of south-eastern Australia. The first cave and sinkhole dives here took place in the very late 1950s, and until the mid 1980s divers generally used single diving cylinders and homemade torches, and reels, resulting in most of their explorations being limited.

A series of tragedies between 1969 and 1973 in which 11 divers drowned (including a triple and a quadruple fatality) in just four karst features - "Kilsbys Hole", "Piccaninnie Ponds", "Death Cave" and "The Shaft" - created much public comment and led to the formation of the Cave Divers Association of Australia (CDAA) Inc. in September 1973. As a consequence of the CDAA's assessment programs, divers are rated at various levels, and today they comprise Deep Cavern, Cave, and Advanced Cave.

During the 1980s the Nullarbor Plain was recognized as a major cave-diving area, with one cave, Cocklebiddy, being explored for more than 6 kilometers, involving the use of large sleds to which were attached numerous diving cylinders and other paraphernalia, and which were then laboriously pushed through the cave by the divers. In more recent years divers have been utilizing compact diver-towing powered scooters, but the dive is still technically extremely challenging. A number of other very significant caves have also been discovered during the past 10 years or so; the 10+ (Lineal) kilometre long Tank Cave near Mount Gambier, other very large features on the Nullarbor and adjacent Roe Plain as well as a number of specific sites elsewhere, and nowadays the cave diving community utilizes many techniques, equipment and standards from the U.S. and elsewhere.

The CDAA is responsible for the administration of cave diving certification in Australia and mixed-gas and rebreather technologies are also now able to be used in many sites. All cave diving in the Mount Gambier area as well as some New South Wales sites and the Nullarbor requires divers to be members of the CDAA, whether in the capacity of a visitor or a trained and assessed member.

Brazil

In Brazil there is cavern diving in Chapada da Diamantina, in Bahia state; Bonito, in Mato Grosso do Sul state; and Mariana, where there is also cave diving (visiting Mina da Passagem), in Minas Gerais state.

To dive in public parks, for example those in Bonito, one must be adequately certified by an agency recognized by IBAMA - Instituto Brasileiro de Administração do Meio Ambiente, a federal organ. For cave diving in Mariana a cave diver certification will be required.

Sardinia Italy

The Nereo Cave "Belvedere" watching terrace, south upside entrance

In the north west of Sardinia, close to Porto Conte bay, Alghero territory, there is the most important cave diving site in the Mediterranean Sea. Thanks to the huge limestone cliffs of Capo Caccia and Punta Giglio there are more than 300 caves above and below water, with about 30 large, and many smaller, underwater sea caves. The Nereo Cave is the most important and it is considered also the largest in the Mediterranean Sea. On the east side of Sardinia there are many underwater cave systems starting from the Gennargentu Mountains, with underwater rivers which arrive at the sea by different, lengthy routes. Here one of the deepest fresh water caves exits at more than 110 m (360 ft) depth.

See also

• William Stone (caver)

Sources

• "Skin Diver Killed in Submerged Cave", The New York Times, May 16, 1955, Page 47.
• Basic Cave Diving: A Blueprint for Survival, Sheck Exley 1977.

External links

• Florida Cave & Cavern List
• An article from the CDG
• Woodville Karst Plain Project
• Wakulla system
• International Underwater Cave Rescue and Recovery (IUCRR)
• Article in Divetime.com
• A cavern dive video

Training organizations

• National Association for Cave Diving(NACD) (U.S.)
• National Speleological Society, Cave Diving Section(NSS/CDS) (U.S.)
• {http://www.psai.com/ Professional Scuba Associations International (PSAI)
• International Association of Nitrox and Technical Divers(IANTD)
• Cave Diving Group (CDG) (UK)
• French Diving Federation (FFESSM) Cave Diving Committee (France)
• Cave Divers Association of Australia (CDAA) (Australia)
• Global Underwater Explorers (GUE) (U.S.)
• Cave Diving and Research Group (MADAG) (Turkey)