The Complete Guide to Cave Diving

What is the Difference Between a Cavern and Cave Diver?

There are several key differences between cavern and cave diving.

Cavern diving usually takes place at the mouth of a cave. While there are overhead obstacles, the environment is still illuminated by daylight.

The National Speleological Society’s Cave Diving Section (NSS-CDS) defines cavern diving as diving in an open area that receives direct sunlight, is no deeper than 70 feet, and is within 130 linear feet of the cave entrance.

Basically, cavern diving is a daytime activity that isn’t too far removed from open water diving.

Cave divers, however, can dive miles under water, and go into areas without natural light, as well as limited water visibility.

Another main difference between the two is that one is an extreme sport, while the latter, cave diving, is a specialty qualification that only the top 1% of divers can attain.

Equipment-wise, cavern and cave divers also differ widely, but we’ll go into greater detail in a bit later.

Finally, cave divers have specialist terms for clear water and murky water dives - spring and sump.

What is a Spring?

You know those lovely cave diving shots that are printed in National Geographic?

Shots that look like this:

Well, these photographs are normally taken in spring dives.

On spring dives the water is normally clear-flowing subterranean ventures — sites like the famous Florida spring where all you need to do is maintain your buoyancy and swim with the flow.

Of course, you will need to keep your hand on the guideline.

What is a Sump?

A sump expedition, on the other hand, is through wet and dry cave networks.

Visibility in the water is low, and you are required to surface into small cave pockets. A famous example of this would be the story that captured the global community in 2018 – the Thai Cave Rescue, where divers saved the Wild Boars soccer team from the Tham Luang cave system.

Sadly, Saman Kunan, a former Thai Navy SEAL, died of asphyxiation while delivering oxygen between chambers. His dive buddy was unable to revive him even after performing CPR in the cave network.

In the wake of the tragedy, the Thai Navy has now included cave diving in its training program, so if instances of Monsoon flooding happen in their cave networks in the future, they won’t need to rely on an international team of experts.

Make no mistake - cave diving is an incredibly dangerous activity. You need the temperament, experience, and skill to safely navigate dangerous situations.

The Dangers of Cave Diving

Every level of diving comes with its own set of risks.

In the introductory course of the Open Water Certificate, you are taught to manage stressful situations. But when scuba diving in open water, you always know that by swimming up you will reach the surface.

In cave diving, even if you knew which way was up – it wouldn’t matter. Stress is heightened by the fact that the path to safety can be in any direction.

To prepare for cave diving, divers have to master a lot of drills.

These include:

• How to deal with situations where your tank runs out of air;
• Addressing equipment failure;
• What to do if you lose your dive buddy in the cave;
• What to do if your dive buddy gets tangled in the line;
• What to do if you lose the line that connects you to the exit of the cave.

As you can tell from the list above, these are extreme situations. But cave diving courses, which are operated by their own board of specialists, also include exercises where swimmers’ masks are blinded, and they can only navigate with the guideline.

If you think you’re not able to deal with situations above, even in training, then cave diving is something you should avoid. As the name of the PADI Specialty Course suggests, you need to have no fear when cave diving.

You will also need to continually engage in training exercises, as practice makes perfect.

But just like you need to walk before you run – you have to put in many open water diving hours before even considering cave diving.

What Certificates and Skills Do You Need to Become a Cave Diver?

So you’re determined to become a cave diver, huh?

Well, before you set off on your first adventures, you’ll need to tick off the following steps:

• Firstly, you will be required to complete an Advanced Open Water course, which allows you to dive to 130 feet.
• This certificate then needs to be followed by a specialist course related to cavern diving, which allows you to experience with overhead environments and low-light conditions.
• Finally, you’ll be required to complete a night diving course as caves are not exactly known for being abundant with light.

Only when you’ve ticked all these boxes can you start the plan to embark on a cave diving course.

During your diving education, you will learn about the different types of underwater caves.

There are four types:

Littoral (Sea) Caves

Created by waves and are normally not terribly long. Found mostly in coastal regions, examples of these can be found in the Great Lakes, New England, and California.

Coral Caves

Are what the name suggests: large formations of coral reefs growing together to form closed off caves. These are normally tunnels and are home to fish and sharks.

Lava Tubes

Are formed by volcanic activity. When lava flows from a volcano and hits the sea, the surface cools and hardens. Inside the lava is still moving, creating a tube. As you’d expect, you can find stunning lava tubes in Hawaii.

Solution Caves

These are formed over eons. Water containing carbonic acid seeps through the limestone and dissolves the rock at the lower level, creating the cave structure. Florida’s cave network is an example of this type.

Diving Techniques

While it’s all good and well to have the certificates and know what type of cave you’re exploring, you will need to possess instructor-level buoyancy control, and perfect multiple propulsion techniques, including:

- Frog kicks;

- Flutter kicks;

- Back kicks;

- and Helicopter turns.

These are especially crucial for cave divers as bad techniques will stir up silt on cave floors and ruin visibility — not a problem in open water situations.

If you've been able to tick all the qualification boxes and have the skill set nailed down, now you need to ensure that you have the right gear.

Cave Diving Equipment

As we’ve highlighted so far, cave diving is a highly specialized activity.

For cavern diving expeditions you only need to use a single tank with K-valves and a single regulator.

Cave divers, however, use systems with two separate on/off valves and regulator first stages. This means if your valve-to-regulator O-ring should rupture, or a regulator begins to free flow, you can still shut off the problem equipment and use the second tank.

Most of your scuba gear will need to be reconfigured to ensure that entanglement risk and silt kick-up is reduced. So, all gauges, inflator hoses, and regulators are fitted, or stowed on the suit, tightly. Flapping fin straps need to be taped down too.

Then, fairly obviously, your snorkel is left behind. You can’t reach the surface in the cave. Also, they tend to get caught on obstacles on the ceiling of the cave.

I can’t stress this enough - entanglement is a massive risk for cave divers; everything has to be strapped down. Flapping fin straps need to be taped, and other accessories need to be stowed away or attached to the body with straps.

The most crucial piece of equipment to a cave diver is their reel. This line is laid down as the divers explore the cave network. Without it, there’s no guideline back to the entrance of the cave. Even if conditions are clear, a lousy kick of the fin can ruin visibility.

A cave diver’s rope is literally their lifeline.

You will always need your wetsuit, even in tropical climates, as the lack of direct sunlight means temperatures in caves are low. Also, gloves are not recommended as divers need to be able to rely on their sense of touch when navigating dark spaces.

Best Lights for Cave Diving

Caves are dark.

To navigate, it is crucial to have a minimum of two lights: a primary light and a backup. Most cave divers prefer a canister style light for their primary and various secondary lights mounted to their helmets or attached to their BC.

We recommend our Aqualite Pro2 and the SL4 eELD for lightweight, compact secondary options. Both have a bright, narrow beam that make it easy to see down long passageways.

The SL3 is a great option for a easy to reach emergency backup light because it can be attached directly to your BC with a retractable leash.

The Final Word

An activity this dangerous is a pull for individuals who like to test themselves and push the limits of their ability.

There’s also something to be said about finding a cave that’s never been seen by humans before. In a world running low on new frontiers of adventure, the underwater cave offers an opportunity to experience genuine exploration.

Just be careful down there.