Cave diving

Cave diving is a type of technical diving in which specialized SCUBA equipment is used to enable the exploration of natural or artificial caves which are at least partially filled with water.

The attraction

Water-filled caves attract divers and speleologists for several reasons:

they are often unexplored or little explored
they present a technical diving challenge
they have a wide range of unique physical features such as stalactites and stalagmites
they may contain unique flora and fauna not found elsewhere

Hazards

Cave diving is one of the most challenging and potentially dangerous kinds of diving for several reasons:

is a form of penetration diving: in an emergency the diver cannot ascend directly to the surface but may have to swim horizontally
the exit route may be a considerable distance and may be deep. This means the diver needs sufficient breathing gas to make the journey and deep diving risks and problems may be encountered
the cave system may be difficult to move through: there may be narrow gaps, currents, low visibility and it may be very difficult to remain on the exit route

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. One such example involved a pair of very experienced cave divers who were trapped inside a cave when a section of the roof collapsed, blocking their only exit route.

Cave diving includes all of the hazards present in open-water SCUBA diving, and adds many new hazards:

Caves have ceilings, which prevent divers from making direct ascents to the surface in emergencies. Instead, a cave diver must travel all the way back to the cave entrance before being able to ascend to the water's surface.
Caves are dark. 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 in such places is described as clinical darkness, meaning that it is impossible to see without an artificial form of light.
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.
Caves often contain sand, mud, clay, silt, or other sediment that can reduce visibility to zero in seconds when carelessly stirred up.
Caves can contain tight passages, which require special techniques to navigate.
Caves can visually confuse the diver. It is not difficult to become lost in a complex cave, which is why all cave divers use guidelines to keep track of the way out.
Caves can present environmental dangers like cave-ins.

Safety

Most cave divers recognize five general rules for safe cave diving:

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.

Guideline: A continuous guideline 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 guideline is the number one cause of fatality among non trained, 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. 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. 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 and ended for all members of the dive team.

Please note this article cannot substitute for actual cave-diving instruction. While these rules sound very simple, cave diving requires a wide variety of very specialized techniques. Many divers have died because they did not appreciate how difficult it is to correctly implement these five guidelines. For example, many divers have died because they attempted to adhere to the guideline rule, but did so improperly, using water-ski rope (which floats), or an improvised reel which entangled them in their own guideline.

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.

The cave diving community has worked hard to educate the public on the risks they assume when they enter water-filled caves. Warning signs replete with 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. Cave diving instruction is relatively inexpensive and a lot of fun; there simply is no reason to attempt cave diving without proper instruction or equipment.

International differences

The cave diving community is a global one. Cave diving practice can differ markedly by locality. While most cave divers in the US would balk at the use of any sort of floating polypropylene guideline, 6mm polypropylene line is the norm in UK sumps 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. On the continent (Europe), in larger sumps, thinner yet slightly buoyant line is typical. This disagreement illustrates that you must contact your local organisation for cave diving to learn from the experience of others - often that experience has been bought with people's lives. Cave diving practices in some localities may be different than those in other parts of the world because those caves require specialized techniques. Always contact someone familiar with a cave before venturing inside it.

Regularity in signs and warnings may also differ around the world. For example, warnings signs are rare in the UK, and are also frequently ignored with fatal consequences.

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. The number of day lit sumps in the UK is small, perhaps fewer than a dozen with any appreciable penetratable sump behind them. Also, the process of learning to cave will automatically give you an appreciation of the seriousness of cave diving. Most people start to cave unaware of the existence of cave diving, then go through a period when they see the water disappearing into the sump and wonder where it goes. Then comes a phase when they see the guideline disappearing into the sump and they ask themselves how on earth people can be so insane as to even contemplate diving down that squalid, constricted hole. Then the fear starts to get to them, because realise that they are contemplating diving down that squalid little hole to get to the dry cave on the far side. The fear abates after a time and is replaced by a zen-like feeling of resignation. If you reach this point, and can control your own instincts, then perhaps you're ready to learn to dive. Always seek out instruction before attempting to dive, however. Martyn Farr's excellent book The Darkness Beckons (ISBN 0906371872) has a most excellent title - if cave diving is for you, then the darkness will beckon you; if it doesn't beckon, don't go chasing it.

Some people have come to cave diving directly from the diving community, but they're far in the minority in the UK, and represent only a few percent of the CDG. They've universally become competent and keen dry cavers in the process of learning to cave dive. As is said in the UK, Come on in! The water is horrible, cold and full of mud.

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.

Cavern Diver

Cavern training will lay down the basic skills needed to enter into the overhead environment. The training will generally consist of

gas planning
propulsion techniques needed to deal with the silty environments in many caves
reel and handling
communication

Once certified as a cavern diver, a diver may enter the overhead environment with certain limitations which will include limits on penetration distance, visibility and others.

Intro Cave Diver

Intro to Cave training will build on the techniques learned during cavern training and will include the training needed to penetrate beyond the cavern zone and working with permanent guide lines 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 1/6th of double cylinders. An intro cave diver is also not allowed to do any complex navigation such as going past a split in the permanent line or venturing off the permanent line.

Apprentice Cave Diver

Apprentice Cave training serves as the building block from intro to Full and includes the training needed to penetrate deep into the cave working from both permanent guide lines as well as limited exposure to sidelines that exist in many caves and serves as an introduction to 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 has one year to finish full cave or must repeat the apprentice stage.

Full Cave Diver

Full Cave training serves final level of basic training and includes the training needed to penetrate deep into the cave working from both permanent guide lines 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. An 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.

Advanced Cave Diver

Stage Cave Diving
Sidemount Cave Diving
Diver Propulsion Vehicle (Training for use in caves, permitted use only after certified Scuba Diver)
Survey

History

The beginning

Jacques-Yves Cousteau, co-inventor of the first SCUBA equipment, was both the world's first SCUBA diver and the world's first cave diver. SCUBA diving in all its forms, including cave diving, has advanced in earnest since he introduced the Aqua-Lung in 1943.

US history

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.

The largest and most active cave diving community in the United States is in the panhandle of northern Florida. The North Floridian Aquifer expels groundwater through numerous first-magnitude springs, each providing an entrance to the aquifer's labyrinthine cave system.

The largest underwater cave in the USA is the Wakulla system, which is explored exclusively by a very successful and pioneering project called the WKPP.

Cave Diver Fatality

Navy Lieutenant Murray Anderson was twenty-eight years of age, a resident of Fort Valley, Georgia. His experience as a diver amounted to 200 hours of underwater exploration.

Anderson died in May 1955 while exploring an underwater cave in Radium Springs, Georgia. Divers found his body near a guide rope which would have led to safety for him. Four US Navy diving experts from Charleston, South Carolina spent the night of May 15 searching in darkness prior to locating him.

A coroner's jury was preparing to investigate Anderson's death.

The cavern was previously uncharted. An electronics technician, Donald R. Gerue, was assisting the Lieutenant in the cavern dives. Gerue was from Pontiac, Michigan and was associated with a Naval Reserve unit.

The two men discovered the cavern a distance of seventy feet below the surface. It is one of many which form an intricate honeycomb at Radium Springs. Mr. Gerue said that visibility was only six inches, even with the use of powerful lamps.

Anderson and Gerue began exploring the "silt-filled maze" around 6:30 P.M. on May 14. They used aqualungs.

Lieutenant Anderson was married and the father of two small children.

UK history

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 4th October 1936 using a home-made drysuit surface fed from a modified bicycle pump, which allowed Sheppard to pass Sump 1 of Swildon's Cave. 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.

(Normal practice in UK caving is to number sumps and sections of open cave, not exploration limits, but Wookey is a special case. At the time of writing, Wookey is still at limit 25 in the eighth sump. At the other end of the system, Swildons has been pushed to sump 12 and is still giving people "interesting times.")

It is also worth noting that one of the front-line divers in these early operations was a woman, Penelope Powell ('Mossy'), which must have created quite a lot of comment at the time.

The number of sites where "standard 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". That's "Apparatus For Laying Out Line And Underwater Navigation", a god-awful contraption 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 Mike Wooding (and others) developed new techniques using wetsuits (which provide both insulation 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.

The definitive volume on the history of UK cave diving is Martyn Farr's The Darkness Beckons, ISBN 0939748320, which has been through 2 editions (1980, 1991) and was written by a major figure in UK diving at a time when many of the original participants were still alive and available for interview.