What is the Difference a Cave and a Cavern in scuba diving?
Photo by Marek Okon / Unsplash

Cave. Cavern. Same. Same. Well in a way that is true. We all use the terms ‘cave’ and ‘cavern’ interchangeably. This blurs the differences between the two. You might use the term cavern incorrectly in a conversation. The only person calling you out on your error is your Geologist friend. Without writing a thesis in geology, let’s look at the definitions and origins of these terms and then bring the question ‘What is the difference between a cave and a cavern’ within the context of scuba diving.

What is the Difference Between a Cave and a Cavern?

The definition of a cave is officially defined as any hollow in the earth. Caves can be naturally occurring or man-made, with horizontal or vertical openings into a rock formation. Furthermore, some portion of the cavity needs to be void of direct sunlight.

In contrast, caverns are naturally formed in soluble rock and have the ability to grow stalagmites and form speleothems. Caverns are often a system of chambers. All Caverns are caves, whereas not all caves are caverns.

So, not as clear a difference as I thought either.

Yet all the time we hear these two terms defining a huge difference in scuba diving. Cave Diving is immediately perceived as hardcore and one of the deadliest recreational activities on the planet. Whereas Cavern Diving is offered as a specialty course by PADI and easily obtainable by any Advanced Open Water certified diver over the age of 18.

Cave Diving

Most recreational scuba diving relies on redundancy and direct access to the surface. A newly certified diver can dive independently as long as they have a buddy. If they lose their buddy, they both ascend directly to the surface keeping to maximum ascent rates.

A procedure like this is not possible if you are penetrating a cave system on your dive. Any problem is exemplified by the fact that you need to first find your way back out and then access the surface near the entrance / exit.

Large recreational training bodies such as PADI do not offer full cave certifications due to the high risk and often very localised knowledge needed to penetrate a cave safely.

TDI (Technical Diving International) on the other hand offers full cave courses.

Learn about the different types of scuba certifications

Therefore ‘cave diving’ is the practice of penetrating an underwater passage beyond the natural light zone. These dives sometimes require the passing of underwater restrictions that require gear removal. Cave divers use lines as references during these dives. Most cave divers rely on their own gas plan and do not rely on a buddy for backup gas. They are independent and conduct the dive as a group, but are responsible for their own safety.

Cavern Diving

A ‘cavern’ in diving is a flooded hollow with a restricted entrance. Often these are entrances to a larger cave system beyond them. The golden rule is the light penetration zone. Cavern divers always remain within the natural light zone with direct access to the exit/surface. Some cavern diving courses include a maximum allowed distance from the exit to atmospheric air, keeping divers safe.

Cavern diving courses are often an introduction to cave diving. Cavern divers still rely on their buddies in emergency situations. It is still a good idea to follow the general rules of what divers should do for their own safety.

To get a feeling for how demanding and potentially deadly cave diving can be, I can highly recommend the documentary film Diving Into The Unknown, which tells the story of a group of cave diving friends from Finland.

Watch the trailer below.

There you have it. When asking ‘What is the difference between a cave and a cavern’ we really need to consider the context this question is asked in. There is a geological difference that has little effect in scuba diving. However, this classification in the diving world between a cave and a cavern makes a massive difference.

Always dive within your training and limits. The Last Dive is a fantastic book that tells the tragic tale of a father and son team of divers that pushed their training limits too far.