Cave Diving is a type of technical diving in which specialized SCUBA gear is used. In the U.K. it is an extension of the more common sport of caving, and in the United States an extension of the more common sport of SCUBA diving. Compared to caving and SCUBA diving, there are relatively few practitioners of Cave Diving. This is due in part to the specialized equipment and skill sets required, and in part because of the potential risks.
Despite these risks, Caves Diving attract SCUBA divers, cavers, and speleologists due to their often unexplored nature, and present divers with a technical diving challenge. Underwater caves have a wide range of physical features, and can contain fauna not found elsewhere.
Most cave divers recognize five general rules or contributing factors 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 successive segment focusing on more complex aspects of cave diving.
- Guideline: A continuous guide line is maintained at all times between a dive team and a point outside the cave entrance in open water. Then 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 line and easily follow it back to the exit. Failure to use a continuous guide line to open water is cited as the most frequent 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 used. Cave divers are advised to keep in mind this effective difference between open water depth and cave depth. It should be noted that among fully trained cave divers deaths, excessive depth is frequently cited as the cause.
- Gas management: The most common protocol is the “rule of thirds,” in which one third of the gas is used for penetration, one third for exiting, and one third to support another team member in the case of an emergency. The rule of thirds makes no allowance for the increased air consumption that the stress caused by the loss of an air system will induce. Dissimilar tank sizes among the divers calls for gas matching and the proper amount of air reserve must be calculated for each dive. One school of thought is to assume that anyone else diving with you does not exist, as sometimes there is absolutely nothing that you can do to assist him/her. 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 the cave. 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: Each cave diver must have three independent sources of light. One is the primary and the other two are backup lights. Each light must have an expected burn time of at least the planned duration of the dive. 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
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 Diving training explains the basic skills needed to enter into the overhead environment. Training consists of gas planning, propulsion techniques, reel handling, and communication. Once certified as a cavern diver, you may undertake cavern diving, as well as advance into cave diving training.
- Introduction to Cave Diving 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 1/3 of a single cylinder, or in the case of a basic cave certification, 1/6 of double cylinders. An intro cave diver is not certified to do complex navigation.
- Full Cave Diver training is the final level of basic training and includes the training needed to penetrate deep into the cave working from both permanent guidelines as well as jumping to 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 1/3 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.
- 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.
- In the 1970s, cave diving greatly increased in popularity among SCUBA divers in the United States. However, there were few experienced cave divers and no formal classes to handle the surge in interest. The result was a large number of divers Cave Diving without any training. This resulted in over 100 fatalities during the course of a decade. Florida came close to banning SCUBA diving around cave entrances. Cave Diving organizations responded to the problem by creating training programs and certifying instructors, besides other measures to prevent these fatalities which included posting signs, adding no-lights rules, and other enforcements.