Inspired by Sheck Exley’s publication “Basic Cave Diving: A Blueprint for Survival” (1977), most cave divers follow five basic rules for safe cave diving. The rules of safety are training, guide line, depth rules, Air (gas) management and lights. To remember these safety precautions, divers use the mnemonic terms “The Good Divers Are Living” or “Thank Goodness All Divers Live both which take the first letter of each rule to create a clever saying.
The first rule of safety is training. Certification is typically taught in segments, with each stage of training focusing on increasingly complex aspects of cave diving. Concurrently with training, divers must complete stages of training in the real world before advancing to the next level of certification.
Another rule of safety is to use the guide line. The guide line is a continuous line that is maintained between a fixed point outside of the cave (in open water) and the leader of the dive time. It is important that the dive leader lay the line with sufficient tension. Should visibility in a cave be diminished, often caused by “silt out,” the dive team can search for the taut line and follow it back cave’s entrance.
Depth rules is also something that divers should acknowledge. By respecting the established dive plan or maximum operating depth (MOD) of breathing gas mixtures, divers can avoid conditions such as nitrogen narcosis and oxygen toxicity.
Air management or gas management is another safety rule for divers. Typically adhering to the “rule of thirds,” divers should dedicate a third of their gas supply to start the expedition, a third for egress, and the last third as back up should a diving teammate need it in an emergency.
Having light is also a cave diving safety rule. Divers should have three independent sources of illumination: one primary light and two backups. If any of the three lights fail for a diver, the dive is called off for the whole team.
