Cavern diving is the exploration of overhead environments while remaining within sight of daylight.

• Cave divers may penetrate thousands of meters or yards. In contrast, cavern divers generally go no further than 60 m/200 ft from the surface.

• Additionally, cavern divers keep the entrance clearly in sight at all times.

• Like cave divers. cavern divers use a guideline so that, should they accidentally lose sight of the entrance, they can immediately regain it.

By taking these steps, cavern divers remain able to make independent emergency ascents. This helps restore the safety margin they enjoy in open water. Properly trained and equipped wreck and ice divers who wish to remain within sport diving limits take similar steps.

Because cavern divers remain within the independent emergency ascent zone, while cave divers go far beyond it, there are several other significant differences between cavern and cave diving.

• Cavern diving is, by definition, a form of sport diving. This means that divers can obtain Cavern Diver certifications from agencies such as NAUI, PADI and SSI.

• In contrast, cave diving is a form of technical diving. As such, Cave Diver certification is available only through organizations such as the National Speleological Society Cave Diving Section (NSS-CDS), TDI, IANTD, etc.

The risks that cavern divers must manage are not significantly greater than those they experience in open water. This means that, if they choose, they can use much the same equipment as “normal” sport divers.

Cave divers, on the other hand, use highly specialized equipment. One such example is gas-delivery systems.

• Cavern divers can, if they choose, use single tanks with K-valves and a single regulator first stage.

• Cave divers use systems with two separate on/off valves and regulator first stages. Should a valve-to-regulator O-ring rupture or a regulator begin free flowing, cave divers can shut off the offending regulator/valve combination and exit using the remaining regulator and valve.

• Because cavern diving is still a form of sport diving, with modest risk factors, it is an activity that a number of experienced recreational divers can learn and enjoy.

• Cave diving, in contrast, is for a far more select group of individuals.

Cave divers should possess near-instructor-quality buoyancy control and general diving skills. They should be utterly committed to diving in a highly disciplined and methodical manner and have an above-average understanding of the technical aspects of diving.