Caves and caverns, like wrecks, create an arena for divers offering fantasy and time travel. Their environment introduces an unknown element that perpetuates challenge and human endeavor, an intrinsic reaction in human behavior (to explore). For many, the bowels of caves and caverns are foreboding environments that conjure feelings of claustrophobia, darkness and insidious fates. Yet with training and experience, diving in caves can be rewarding and very safe. Cave diving pioneer Tom Mount describes exactly why cave environments intrigue me to the degree they do;
"Caves are passages into a world of intrigue, a dreamland where fantasies often abound."
The ancient Maya of Central America believed caves to be a watery window the dead used to reach the underworld. For many, they provide a secret duct into a world of mystery, a nirvana where dreams become reality. Then there are the extremists who test the limits by pushing distance and depth to set records.
Within the realm of caving and cavern diving, there is a magnificent diversity of overhead environments from warm water Caribbean caves to frigid sumps in the far reaches of the northern hemisphere. The physical variation between the two types of settings includes not only the water temperature and flow, but the land environment that has been carved to form the cave.
Take coral caves for example. Between two very deep ocean canyons in the Caribbean Ocean, is a limestone ridge that barely rises above the sea. Upon this crest lie the Cayman Islands, a place I was fortunate enough to explore for eighteen months. Much of its shoreline is marked with petrified coral that has eroded into sharp hellish-looking landscapes. Like blackened fire wisps frozen in time, these fossilized features are part of the geomorphology that extends from the underground waterbeds inland to the living reef encircling each of the islands. The tunnels in between are what many have come to know as the caves and caverns of Cayman. Their existence marks a thumbprint from which we can see history. They tell tales of how this place came to be – and likely what it will eventually become. They are literally passageways through time.
Throughout the Cayman Islands, there are many shallow caverns and tunnels created by shore erosion and wave action such as the grotto area just south of Georgetown. Others are quite intricate and formed as a result of a unique and dynamic coral evolution like ‘The Maze’ on the island’s east end. It is difficult to explain the feeling of weightlessness and wonder that the warm Caribbean Sea offers a diver – especially to a non-diver. It is even more difficult to describe the experience of diving through a tunnel filled with brightly coloured soft and hard corals.
Some caves are fresh water filled and serve as a basin for the rain that falls and settles on these low-level islands. Many of these systems actually lead out into the ocean where they drain through a myriad of limestone and coral formations. In one particular system on Grand Cayman known as the ‘Green Hole’, the cooler fresh water spills out into the salty ocean from a small crack in a collapsed part of the reef more than 300 meters from shore. The different densities of these colliding waters create a green and blue boil with a very definite halocline. This anomaly provides an interesting contrast to the typical cobalt blue that saturates the shallow reef areas, making it irresistible for the adventurous divers.
One afternoon I decided to cruise along a portion of the wall on the southeast side, to see how many ‘passageways and caverns’ I could find. It was perfect timing as that time of year, the Silversides (a tiny fish which, in the juvenile stage, school together in the tens of thousands) are abundant in overhead environments. As I explored one tunnel, I was amazed at how the thick coral walls rose up high above me, meeting to create an arching ceiling. I followed the sandy, sinuous trail which finally spilled out into the Cayman Trench. It was literally the light at the end of the tunnel. I swam out of the opening and hovered on the wall looking back at the hole from which I had just emerged; it was now a small shadow hidden in the enormous coral cliff face. Revelling in the sensation of floating in space with the ocean floor so far beneath me, I began searching the wall for another hole, another door to these tunnels. It did not take long before I found a second entrance, and again, I was exploring beyond what felt like any sense of time, just space.
Beams of sunlight, fractured by the dense ocean water, pierced through the small holes in the coral roof and bounced off a group of large shiny Tarpon hovering motionless in one of the caverns. They lethargically moved into the next chamber where a mass of Silversides were hiding. As the Tarpon moved on, they split the cloud of small fish before resting in a far end of the tunnel. The school of shimmering Silversides spread and encompassed the intruders, maintaining a proximity that perfectly mirrored the shape of their larger predators. Following the big fish, I was in awe to see the minnows surround me as well, mimicking my body position, regardless of how sudden or subtle a move I made.
I approached the final restriction where the passageway cut sharply to the right, only to discover that the floor of the tunnel suddenly stopped and a skylight opened up. It popped me out on top of the reef in about 40 feet of water and it took a few minutes for my eyes to adjust to the sudden increase in ambient light. Diving through the coral tunnels of Grand Cayman was an exhilarating experience and made me think that this was very much like an imaginary world. But as I swam away from the reef, the cavern entrances disappeared in the camouflage of the complex reef structure, and along with it the sense of timelessness and fantasy.
Coral cave environments are quite different than the limestone structures found in an area in north Florida known as “cave country” by divers. Carved by high flows of fresh water, the rock literally dissolves into smooth round tunnels that wind and stretch in a number or directions. The topside landscape provides no indications that miles of Karsts are hidden below except for the fresh water springs that pop up occasionally in the middle of nowhere. There are also a number of rivers from which crystal clear water flows, billons of gallons each year, where locals can be found tubing and swimming to escape the heat. The cave diving industry in Florida has become immensely popular, drawing divers from all over the world. The sites are now set up to host the onslaught of people comfortably while minimizing the damage to the environment.
A lot of the actual cave systems are located in State and County managed parks where staff have constructed paths and parking right up to the dive site. A diver now need only back his van up to a picnic table, unload, don his gear and walk a few feet to a set of stairs that leads down to the entrance of the cave. Most of these systems have permanent guidelines that begin a few feet into the cave. Once inside, there is an endless number of paths you can choose with lots of side passages. The chambers and passages vary from large rooms to tight restrictions requiring side mount configurations. Unlike the coral caves in Cayman, the marine life in Florida’s caves is less dense. Many of the critters have never been exposed to the light of day and are not only blind but devoid of pigment, excluding of course the gators you sometimes find sun tanning at the spring’s edge.
Mexico is another world. The rock walls and roof are plastered with stalactites and stalagmites. Much shallower, warmer and vertically narrower than the wide Florida systems, the Mexican dive ecology begins deep in the Mayan jungle at small sink holes called ‘cenotes’. Some of these systems extend for hundreds of miles and are believed the link up with the ocean. World-class cavers have been mapping these systems for years and still feel they have yet to get a handle on which passage goes where and for how far.
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