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Diving in Cave Country, Florida

Florida has some of the finest submerged caves anywhere in the world. Cave divers come to tiny northern Florida towns with names like Mayo and Luraville from all over the world. Northern Florida is commonly referred to as Cave Country and if you want to dive here, there are a few things you need to know.

The first thing you should know about cave diving is that it is not for everyone. Cave diving requires a very specific temperament (basically, you have to be nuts), is physically demanding, requires a lot of expensive equipment and training, and is potentially lethal. Most people are not suited to be cave divers; if you think you are, read on, and I’ll explain the basics.

Before you even think about diving in a cavern or cave, you need training; lots of it. Many open-water divers have died in submerged caves due to lack of training. Properly trained cave divers, using the correct equipment, and following the established safety rules almost never get hurt in caves. Their training prepares them for most contingencies and their life-support equipment is fully redundant so even a complete failure of one system is usually not life-threatening.

Below, I’ll talk about some of the specific dangers in submerged caves, the training required to enter them while minimizing risks, and the equipment required to prevent your death when diving in them.

Hazards

Submerged caves contain many dangers to the untrained diver. Accident analysis indicates there are four major causes of accidents in caves.

Failure to run a continuous guideline to the exit
Failure to properly manage the breathing-gas supply
Diving to excessive depth
Failure to dive with three lights per diver

1. Continuous Guideline

Cave divers must always have a continuous guideline to the exit. This line is the only way to prevent getting lost in a cave and is the only way to get out if visibility fails. Many caves have permanent guidelines already in them, but the route a diver takes sometimes jumps from one permanent guideline to another or gaps from the end of one line to the beginning of another. In that case, the diver must use a reel of additional line to temporarily connect the two permanent lines together. Only in this way is the integrity of the continuous line to the exit preserved. Even when the two permanent lines are very close or within sight of each other, a jump/gap line is still required since the visibility in a cave can quickly deteriorate to zero if the fine silt on the bottom is stirred up. Even the most powerful lights will not allow you to see through silt; it’s like swimming in milk (low-fat milk, of course… cave divers are very health-conscious). When a silt-out occurs, the diver can still exit the cave by touch, feeling the continuous line all the way to the exit. If the jump/gap line were omitted, a zero-visibility situation would leave the diver with no way to find the exit of the cave by feel.

2. Gas Management

Cave divers always end a dive and begin their exit when the first team-member exhausts 1/3 of his gas supply. This is known as the Rule of Thirds. It may seem like an overly conservative gas management strategy until you consider what happens if one diver’s gas runs out for whatever reason at the point of furthest penetration. One diver is now out of gas, the other diver used 1/3 of his gas entering the cave and will need at least another 1/3 to exit the cave. That leaves the last 1/3 for the out-of-gas diver. If the dive were turned at 1/2 instead of 1/3, there would be insufficient gas left to get both divers out of the cave; one would drown. If the doomed diver panics at this realization, both may drown. If you consider that during an emergency both divers will be under great stress and likely to be breathing at a higher rate than usual, then even the Rule of Thirds doesn’t provide enough gas to get both divers out of the cave alive. The Rule of Thirds initially seems too conservative, but careful analysis shows it is actually inadequate if the gas emergency occurs at the point of deepest penetration into the cave. It is also inadequate when diving in a siphon where the water flows into rather than out of the cave since the divers will be swimming against the current during the exit portion of the dive.

3. Excessive Depth

Cave divers, like all divers, are susceptible to Nitrogen Narcosis. This is the narcotic effect breathing nitrogen-containing gas mixtures has on the brain. Narcosis becomes worse as the diver’s depth increases. In cave diving, having a ‘clear head’ is critical. The cave diver continuously makes decisions that can affect his and his teammates’ safety. Under the influence of narcosis, a poor decision can be lethal. For this reason, the depth of a cave dive must be appropriately matched to both the narcosis potential of the gas mixtures being used and to the experience level of the diver.

4. Lights

Cave divers always carry at least three (often more) lights each; one primary light and two backup lights. Vision is so central to the way humans function that finding yourself with a failed light and no backup in a cave may mean your death. Even in zero-visibility, alternately cupping and uncupping your light can signal your dive buddy through the silt. Also, if your buddy got lost in a cave and, after searching for him, you were forced to exit due to a low gas supply, you could leave one of your backup lights turned on and clipped to the permanent line in the cave, then exit with your remaining backup light available in case your primary failed during your solo exit. The light you left behind may save the life of your lost buddy if he’s lucky enough to see its glow around a bend in the tunnel.

Training

Cave divers undergo a strenuous, detailed, and comprehensive training regiment before they’re certified. Lack of training can be fatal in a cave. Proper training will include extensive classroom work, reading, hands-on instruction on gear use and configuration, and numerous dives in several different cave systems over at least eight days. Your training will probably also include a number of hair-raising stories told by your instructor. Cave diver training is generally accomplished in four stages:

Cavern Diver
Introductory Cave Diver
Apprentice Cave Diver
Full Cave Diver

1. Cavern Diver

The first phase of training, Cavern Diver, will give the experienced recreational open-water diver a feel for what an overhead environment is like. This is accomplished with lecture and skills training and at least four cavern dives. Caverns are different from caves in several ways. Caverns exist at the entrance to all caves though not all caverns lead to caves. By definition, a cavern is the zone where daylight penetrates. Cavern divers do not dive deep or more than 130 feet total linear distance from the surface. They also always maintain a direct line-of-sight to the surface. This means that, while they may be diving in an overhead environment with rock directly above them, they can always see the surface on a diagonal from their position. Cavern divers always carry a guideline reel used to find the exit in the event that they accidentally lose the direct line-of-sight to the surface.

Cavern diver training can be completed using regular open-water gear as long as each diver uses two regulator second stages (octopus) so a diver can share his gas with a buddy in the event of an out-of-air situation.

The Cavern class is very good training even for those who do not intend to cave dive. The training stresses proper equipment configuration, especially streamlining and the elimination of ‘danglies’ which are things like consoles and regulators that hang down from a diver and can get snagged in crevices. It also teaches various finning techniques used in caverns and caves to avoid disturbing the visibility-destroying silt that settles on the bottom, and it teaches excellent buoyancy control which is critical in any overhead environment. Cavern divers learn to properly use a guideline reel and perform numerous drills to gain skill and confidence in the various techniques involved. After taking a cavern class, most open water divers will immediately see an improvement in their buoyancy control, streamlining, and air consumption. The cavern training course is an excellent investment for most open-water divers, even those who have no interest in cave diving, because it improves the average diver’s skills tremendously.

2. Introductory Cave Diver

The second phase of cave diver training is commonly called Intro. This is where the real fun begins (if you’re not claustrophobic). In this phase of training you will actually enter a cave and experience total darkness. Before you begin this level of training, you should have several hundred double-tank open-water and cavern dives logged. While this level of training could be done using single tanks with special dual-orifice valves, double tanks with fully redundant regulators is by far the preferred configuration.

Intro training begins with a check of your gear and a review of the things you learned during cavern training. It will include at least four cave dives at three different sites.

After the review and gear check, there will be several hours of lectures, open discussion, and skills training. You will learn the basic theory and practical application of that theory needed throughout the rest of your Cave training. Some of the new things you will learn and old things you will reinforce are:

Finding the primary line if you’re lost
Finding your buddy if you get separated
Deploying your backup lights
Following the guideline in zero-visibility
Managing your gas supply
Handling an out-of-air situation
Proper dive and contingency planning

You will be taken into a cave for the first time, and swim farther from daylight and the surface than you’ve ever been. You’ll put into practice everything you learned in the Cavern course as well as new knowledge and skills necessary to survive entering a submerged cave.

Gear

Since at this stage in your training you will be much too far from the surface to swim there if your gas supply fails, you will have to have a redundant source of gas. This can be a “Y” or “H” valve or conventional double tanks.

“Y” and “H” Valves

These valves allow you to put two complete regulators on a single tank. This is not an ‘octopus’ setup like you used in Cavern training. It’s two independent complete regulators. One of the regulators should have a 7’ long hose. In a cave, as opposed to a cavern, it is possible for you and your buddy to enter a tunnel too narrow for you to swim side-by-side. In that case, an out-of-air situation could be fatal. To reduce this risk, one hose must be long enough to reach the out-of-air diver while the buddies swim in single-file. At 7’, the hose is long enough to do this without being unwieldy.

Conventional Doubles

Doubles are two tanks firmly attached to each other with metal bands and a manifold with isolator valve. The manifold allows you to breath the gas in both tanks as if they were one large tank; the isolator valve allows you to isolate the tanks from each other in the case a tank o-ring, burst disk, or other component fails. This can save enough gas in the good tank to allow you to exit the cave. In this system, each tank has a complete, independent regulator which effectively gives you two totally independent life-support systems.

The Introductory Cave Diver training will teach you gas-management techniques that, in most cases, will allow you and your buddy to exit the cave alive even if both your primary and redundant life-support systems fail.

In addition to the gear above, you must also have at least one primary light and two backup lights. This is the minimum requirement and many cave divers use more. You’ll also need good exposure protection in the form of a thick wetsuit or a drysuit (preferred) as well as several guideline reels, clips, line-arrows, and assorted other hardware

3. Apprentice Cave Diver

This level of training is much like the introductory level and much of this training is review and reinforcement of the knowledge and skills you learned at that level. You will learn some new things, however, and you will be expected to have additional gear as well. Some of the things you will learn at this level are:

Diving double tanks (if you haven't already done so)
Decompression diving procedures
Jumping from one permanent line to another
Planning and executing complex traverses

During Apprentice training you will make at least four cave dives at three different sites using double tanks; single tank diving is not permitted at this level of training. If at all possible, you should already have several hundred open water dives using doubles so you can concentrate on learning how to cave dive without the distraction of learning to dive double tanks at the same time. You’ll also be spending much more time inside the caves; this will require decompression diving techniques and equipment. You’ll learn how to perform jumps where you leave the main permanent line and jump to another after connecting them with a jump-reel, and you’ll learn to plan and execute traverses where you enter the cave system at one place and exit at another. You’ll also hone your skills using a guideline reel and your buoyancy control and finning technique will continue to improve. By this stage in your training you should own or be ready to make the commitment to owning all of your gear.

4. Full Cave Diver

This is the final level of training. In it, you will review all the knowledge and skills learned in the previous three levels and will extend your bottom time, depth, and linear penetration of the caves over the two days and at least four required dives. Depth will be limited to 130 feet and the emphasis of the training is on advanced techniques. You will be doing extended decompression dives and will be exposed to zero visibility and high-flow conditions. You will negotiate single-file restrictions while in zero visibility and sharing air with your buddy. You will learn touch-contact communication techniques used in zero-visibility and will learn to plan and execute complex dives such as traverses and circuits. A circuit is a dive in which you swim a full circle and arrive at your starting point from a different tunnel then the one you entered.

By the time you finish this level of training, you should have all your own gear including double tanks, lights, regulators, and exposure protection and you should be very comfortable diving your gear. Your buoyancy control and finning technique will be nearly perfect and you will be highly proficient with a guideline reel. You will have been exposed to enough drills and varying conditions to confidently handle most emergencies likely to occur during a cave dive. You’ll be one of the most highly trained and proficient divers on Earth outside the military and will have opened a whole new world of places to dive in and explore.

Warning!

In closing, I’d like to emphasize what I said at the beginning of this article: before you consider beginning cave diver training, you should have hundreds of open-water dives in your logbook. You should be so comfortable underwater that you could fall asleep if not careful. I mean this… a cave is no place to be if you’re not perfectly at-home underwater. Additionally, you should be in good enough physical condition to handle the rigorous demands of this type of diving. This includes the ability to walk, sometimes several hundred yards, uphill over rough terrain with 100 or more pounds of gear hanging on your body. You should also have the financial means to buy the very best gear; a cave is no place for a second-rate regulator! This is not a cheap hobby, and if you can’t afford to do it right, don’t do it; you’ll only endanger yourself and your buddies. Above all, DON’T go into a cave without the proper training. Many people, open-water instructors and other highly experienced divers included, have died in caves due to lack of training. It’s telling that even highly trained police divers will not enter a cave when someone is presumed dead in it. They instead call volunteer certified cave divers to search for and recover the body. This happens far too frequently. Please heed my warning!

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