What are the 5 Golden Safety rules of Cave Diving?

Engaging in diving or any sport where one's life is at stake requires adherence to specific rules. While scuba diving involves certain risks, cave diving heightens these dangers due to the unique environment and the inherent challenges of navigating underwater caves. To ensure safety when exploring the depths of a cave, cave divers must follow these five essential rules.

1, Maintain a Continuous Guideline to the Cave Exit

The word "maze" aptly characterizes the layout of most of Tulums cave systems. Many victims of early cave diving accidents mistakenly believed they were navigating a single, straightforward tunnel. They were often startled to find, upon attempting to exit, numerous passageways behind them, all looking the same and making it unclear which path leads to safety.

Adding to this issue is that divers without training in the ultra-precise buoyancy control and anti-silting propulsion techniques taught in cave diving courses often leave a path of reduced visibility. Disoriented divers often believe that swimming towards clearer water will guide them to safety. Ironically, in a cave, this usually takes them further from the entrance.

In many cave diving fatalities, the victims had enough breathing gas to exit when they were at their deepest point of penetration. However, they used up that gas before reaching safety because they were unable to find the exit.

This is why one of the most crucial safety rules for cavern and cave diving is to maintain a continuous guideline that guides divers all the way back to open water. Although the labyrinthine layout of many Mexican caves might briefly mislead divers, correctly used guidelines are reliable.

Laying a guide line

2, Keep Two Thirds of Your Starting Gas in Reserve to Exit the Cave.

Or another way to word it, Always have available double the amount of gas youll need to safely exit.

Throughout the years, there have been several cave-diving fatalities where the victims either knew the exit route or had a reasonable chance of finding it. Unfortunately, they lacked enough breathing gas to reach safety.

Recreational divers often don't consider ascending until the pressure in their tanks falls to between 500 and 1,000 psi. While this might seem obvious, if divers use 2,000 psi or more to explore a cave, exiting with 1,000 psi or less becomes very challenging. When unexpected events occur, such as loss of visibility or the necessity to share air with other divers, the chances of survival in these situations are extremely low. Trained cave divers are taught to reserve at least two-thirds of their initial gas volume for exiting. This "Rule of Thirds" has consistently provided a sufficient safety buffer, even in cases where visibility is poor, contact with the guideline is briefly lost, or gas consumption increases due to anxiety or the need to share air with another diver. There are times when the rule of thirds needs to be dialed back a little bit. In teams of 2 rather than 3 divers, diving to 1/3s may seem a bit aggressive especially in backmount rather than sidemount tank set up. Also if you are diving "down stream" with a current to start with, you should expect to use more gas on your return against the current.

Sidemount Diver

So where did these golden rules of cave diving come from?

So cave diving was getting popular around Florida in the 1970s, recreational divers were finding out about the freshwater springs and just basically using their open water equipment and skills to dive these caves. The inevitable happened and there were lots of near misses and actual fatalities. One guy in particular, Sheck Exley was diving there a lot and had some of his own actual near misses. He decided to change everything, coming up with these theories through his own trial and error until we have The 5 Golden Rules of Cave Diving we still follow to this day. You can read about his adventures and evolution of these rules in his book called Blueprint for Survival. A very good read and a must for all cave divers.

3, Use Three Sources of Light

There have been notable advancements from initial designs, underwater lights are now more powerful, burn brighter for longer and are more reliable. Experiencing total darkness in an underwater cave because of light failure is not something a prepared diver should expect to encounter. However, training for such an incident is a big part of cave diver training. Cave divers should carry a minimum of 3 lights. The primary light should be strong and have a burn time of 1.5 times the planned duration of the dive. 2 backup lights should also be cared in case of a failure to the primary and should last enough time to exit the cave.

Cavern divers, who keep the cave entrance in sight at all times, learn to carry at least one primary and one back-up light each (the sun counts as their third light source). Although almost every cavern or cave diver eventually experiences a dive light failure, the odds that all members of a buddy team will experience a triple light failure are astronomically slim. As once 1 diver loses his primary light the whole team will exit the cave with the diver using his backup light at the front leading out.

Tulum cave diving

4, Remain Within the Maximum Operating Depths for Your Breathing Gas.

While only 10% of cave diving fatalities involve certified cave or cavern divers, 90% of these deaths occur during dives where participants experience an Equivalent Narcotic Depth (END) of 130 feet or greater. At such depths gas narcosis can cause a diver's death or significantly contribute to it. This is caused by their inability concentrate and think clearly due to narcosis.

As technical divers increasingly use breathing gases other than air, there has been a rise in fatalities due to oxygen toxicity (caused by excessive oxygen exposure, such as breathing an oxygen-rich Nitrox mixture at excessive depths) and hypoxia (caused by insufficient oxygen exposure, which can occur when breathing certain Trimix combinations in shallow waters).

Consequently, the primary cave-diver training organizations recommend that divers keep a maximum PPO2 of 1.4 atmospheres while diving and 1.6 atmospheres during decompression. They also advise divers not to exceed an Equivalent Narcotic Depth (END) of 130 feet. Because experts think that both oxygen and nitrogen can lead to impairment at depth, this requires the use of Trimix (a blend of nitrogen, oxygen, and non-narcotic helium) for dives deeper than 130 feet.

It's worth mentioning that although small teams of highly skilled and experienced cave divers are exploring cave systems at depths beyond 300 feet, the typical recreational cavern or cave diver can explore the more popular dive sites around Tulum Mexico for a lifetime without needing to go deeper than 130 feet.

Cave diver in Tulum

Be Trained for Cave Diving; Remain Within the Limits of Your Training and use proper Cave Diving Equipment.

Cave Diving and diving in a cave is not the same thing!

Surprisingly, nine out of ten diving accident victims share a common factor: they have not received formal training on how to dive safely in this unique environment. Due to this lack of training, many victims are unaware of the importance of carrying adequate lights, adhering to the Rule of Thirds, or maintaining a continuous guideline from the cave entrance.

Even when accident victims had formal training and certification as cavern or cave divers, fatalities frequently occurred because the divers went beyond their training limits. Cave Diver training does not equip divers for depths greater than 130 feet. Nonetheless, in nine out of ten fatalities involving trained cave divers, the victims were diving below 130 feet on air. Go figure.

To fully appreciate the breath taking beauty of Tulums caves safely, consider enrolling in at least a five-day Intro to Cave Diver course. This training will equip you with the necessary knowledge, skills, and experience to go beyond the sunlight zone and go where few have been before.

Written by Marc Green of Green Divers Tulum