﻿Coming up, the Blue World team visits a famous Florida cave and and revisits
the rules of cave diving! Welcome to Jonathan Bird’s Blue World.
In the 1960s and 70s, as scuba diving surged in popularity in the United States,
the caves of Florida became an almost irresistable draw for curious divers. However at the time
there was no such thing as cave training. Quite a few people ventured into underwater caves
and never came out. A Florida math teacher named Sheck Exley was among those exploring
the Florida caves. He began analyzing what went wrong when people perished in caves,
and developed a set of rules for cave diving that would help to prevent the most common mishaps.
In 1979, he published a short book Basic Cave Diving: A Blueprint for Survival.
It was the first cave diving manual, and to this day is required reading for cave certifications.
Sheck Exley is considered one of the world’s most important pioneers of cave diving.
It’s a beautiful day in January, and the Blue World team is heading to Florida for a week
of cave diving. Following in Sheck’s shadow, we drive over to Orange Grove
Sink, a cave entrance within Wes Skiles Peacock Springs State Park.
Sheck dove this cave many times, got lost and almost died once. Cameraman Todd had a very close
call here back in the mid-90s too. So what better place for a shakedown dive? Since we haven’t been
cave diving in a few months, we will review our techniques and practice our skills. We begin
setting up our gear. One of the most important parts of cave diving safety is having redundant
breathing gas. So each one of us has two scuba tanks, completely independent of each other.
Cameraman Todd, Cameraman Zach and I will explore Orange Grove Sink as a three person team.
Looks so nice! I super excited we are finally cave diving again! Woo hoo!
This is going to be nice. Oh yeah.
I have a funny feeling that when we get back I’m going to be covered in that duckweed.
We huff our gear down the steps to the water. Back in Sheck’s days,
there were no nice steps here. We don our tanks on our sides, a configuration known as
sidemount. This style of diving didn’t exist back in Sheck’s day, but it has a lot
of advantages. Soon we drop below the water’s surface and head down towards the cave entrance.
Sidemount allows us easy access to the tank valves underwater,
and creates a lower profile so we can easily fit through small openings in the cave. It’s also more
comfortable than tanks on our backs. Todd will be in charge of the line. Cave divers must always
have a continuous guideline to the entrance of the cave to be sure we can find our way out. So
we begin by tying off a reel to a tree branch. Then we follow Todd into the cave.
We pass the stop sign, reminding people that going past this sign
without proper training and equipment can be deadly.
Soon we reach the permanent guideline, where Todd can tie his reel. Once Todd has tied in to the
main line, we now have a continuous guideline out of the cave. Very important. Now, you might ask,
why doesn’t the permanent guideline go all the way out to the light? Because open water divers
might be tempted to follow it into the cave without proper equipment and training!
As we begin our exploration of the cave, we never let that guideline out of our sight. One of the
ways we keep the guideline in sight is by not kicking up any silt. We stay up off the bottom,
and we use a high frog kick. That means we keep our knees bent a bit so our fins stay high off the
bottom, and we use a frog kick that directs water backwards, not down. This is not as powerful as a
flutter kick, but it creates less disturbance of the sediment. If we do it right, the water stays
nice and clear behind us for the trip out. Soon we come across one of the few animals that can
live in this extreme environment: the Dougherty Plain cave crayfish. It has lost all pigment as
an adaptation to living in total darkness. It still has eyes--also without pigment--and
may be able to sense light, but probably cannot see. Not much is known about this species,
and nobody is even sure what it eats to survive in this very low nutrient environment.
Redundancy is the cornerstone of cave diving. And if there is one thing you
definitely need redundancy on, it’s lights. There is zero light in a cave.
If you lose your flashlight, you are totally blind. So Sheck’s rules stipulated no less than 3
lights per diver. You have a primary light, a backup light, and another backup to the backup.
The chances of losing all three are so small as to be almost impossible.
For me, I actually have 6 lights. Two video lights on my camera, plus my primary flashlight,
plus two backups on my helmet and another spare in my fanny pack. I’m not taking any chances!
Since I spend most of my time filming, my video lights are the lights I use the most.
In fact I almost never turn on my primary light except to signal someone.
We have chosen to explore one of the shallower passages in Orange Grove. In his investigations
of cave diving fatalities, Sheck learned that a lot of people get into trouble by diving too
deep. In fact, both Todd and Sheck had close calls in this very cave by going too deep.
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Nitrogen narcosis, caused by high partial pressure of nitrogen, clouds your judgment like you are
drunk. It’s easy to get into trouble when you aren’t thinking straight. So for us, staying
in a shallow passage keeps us safe. The route we are taking maxes out at only 70 feet deep.
Another rule that Sheck proposed is the very famous “rule of thirds.” This cave
diving tenet states that you can use up to 1/3 of your gas supply to go into the cave,
then you turn around. That means that you have 2/3 of your gas remaining when you turn.
It should take another 1/3 to get back out of the cave, leaving the last third as a reserve
in case you have a delay or a failure to deal with. We call this “turning on thirds.”
As a general rule we want to swim upstream in a cave, so that we are working harder to get into
the cave than we are on the way out. That means that getting out is easier and uses less gas.
But even if we know that riding the current out will make it much faster than getting in,
we still turn on thirds. Following the rules is what keeps cave divers safe.
Once you start bending the rules, bad things can happen.
Todd signals that he has hit thirds and it’s time to turn around. We are about 900 feet
into the cave. So now we start heading back, and if we did a good job with our frog kicks,
the water will still be nice and clear on the way out! There isn’t much flow in this cave,
but we are going with the flow on the way out, so it’s a little faster than going in.
We don’t get lost because we’re following that line—the same line we followed on the way in.
Soon we are back at Todd’s reel.
He unties the reel and winds it up as we make our way back up into the cavern zone.
Once we are back out in the spring, we have a little bit of decompression to do.
But it’s not boring because there are Bluegills to film.
Finally, our decompression is complete and we can surface. Woo,
that was great. That was an awesome dive, man. So much fun! Cave diving is still considered a
dangerous sport, but in fact, with proper training and equipment, it has a lower injury rate than
skiing. The fact is, if you get proper training and follow the rules, cave diving is quite safe.
And that is largely due to the efforts of Sheck Exley—the man who used experience and case studies
to write the rules. Those rules are the blueprint to survival in the caves of the Blue World.
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