White Ring Blue Hole was first explored by Tom Turner.
Tom, myself, and Sandra Poucher further explored the cave in May 2000 and produced the map above as well as a video of the cave.
White Ring Blue Hole
As I break the surface of the sea, beads of salt water cascade off my mask and the boat leaps into focus in the bright Bahamas sunlight. Sandra Langston, our support diver, smiles and waves as I swim towards her. She asks how the dive went and I gave a big smile and thumbs up. We've just completed our last video dive and I am anxious to get rid of all the video gear, as well as all the normal equipment required for cave diving.
We are on the "True Blue" anchored about two miles offshore from Long Island in the Bahamas next to White Ring Blue Hole. Blue Holes mark the entrances to a fascinating, underground world formed during the Pleistocene Ice Ages, when the oceans were 300 feet lower and the Bahamas plateau was mostly dry land. Rain dissolved the exposed limestone over thousands of years, carving out extensive cave systems. As the Ice Age ended, the water levels rose and the caves were submerged by the Caribbean Sea. The Bahamas are dotted with hundreds, maybe even thousands of these blue holes and cave divers have been exploring their mysteries since the early 70's.
Tom Turner, expedition leader and fellow cave diver, christened this particular hole, "White Ring" for the band of white sand that surrounds dark blue waters of the submerged sinkhole. Tom started exploring blue holes in 1995 first dove White Ring in 1997 while scouting the area with a local fisherman. He explored over 500 feet of cave passage during the course of a couple dives, enough to know the site had potential. However, he wasn't equipped for a major exploration and the new find was put on hold until now, the spring of 2000.
By now, I have handed up the heavy battery canister used to power the 150-watt, American Underwater Lighting video lights, as well as one of two, side-mounted tanks we are using for cave exploration. I unclip the second tank and hand it to Sandra, and haul myself up the ladder and onto the boat. The boat is rocking in the waves and I take a second to get my balance. At this point, I am glad I don't have to deal with the heavy, double tanks normally used for cave diving.
Usually, a cave diver carries two tanks known as doubles, on his back, connected by a manifold. A system of valves allows the tanks to be accessed either together or individually. The tanks are heavy, about 120 pounds, and by themselves would send a diver plummeting to the bottom like the proverbial "lead weight". To prevent this, a "BC" or buoyancy compensator is attached to the tanks using a backplate and webbing harness. The BC is basically a big balloon and allows the diver to put air in or let air out to compensate for the weight of the tanks.
On the other hand, side-mounts, so called because the tanks are carried one on each side of the diver, are used to explore small passages where back-mounted tanks will not fit, or, as in our case, where the logistics of using backmounted tanks is not practical. Trying to get into and out of a boat thatís rocking with the waves, sometimes violently, and balance 120 pounds of tanks on your back is risky business at best. It's much easier to handle single tanks and in a smaller boat, such as the "True Blue", much easier to store the smaller tanks.
I step back to the stern of the boat and enjoy a brief shower to rinse off the salt before starting the now familiar after-dive routine. The water is warmed from the heat of the generator that provides power to charge our dive lights and scooter batteries and to run the compressor to fill our tanks. It also runs a desalinization plant that provides the fresh water for my shower as well as my first chore: rinsing the gear. I begin by rinsing all the regulators thoroughly to remove any salt. Next I rinse the dive and video lights, masks, and computers. Finally the BC's and wetsuits get a quick rinsing, before hanging up to dry.
Tom, still flush with excitement from a successful video shoot, is busy rinsing the underwater video housing and lights with freshwater before opening the case and retrieving the camera. I hand Sandra the light batteries to put on charge in the boat cabin, where she is preparing lunch. That done, I start taking regulators off the tanks in preparation for filling.
Tom has a custom manifold with four filling hoses so we can fill all our tanks at once off the on-board air compressor. It's slow at two cubic feet per minute, but it gets the job done. I signal Tom that its time to start up the compressor. He flips the breakers in the cabin to provide power to the compressor as I lift up the access hatch. A wave of hot air rushes out of the hold as I reach down to press the start switch. With a roar and a squeal the compressor kicks in and falls to a steady drone as I replace the hatch. I watch the pressure gauge climb as the compressor fills the empty lines with compressed air and then open the valve to begin filling the tanks. A quick check of the tanks to make sure there are no leaks and I'm finally ready to relax.
By now, Sandra has finished lunch and the three of us discuss the next dive planned for this afternoon. This will be our last exploration dive after five days of diving. Months of planning went into this trip. The boat, all of our gear, oxygen for decompression and emergencies, all had to be transported down here. In the short time we've been here, we mapped and explored over a thousand feet of new passage, shot video to document the cave, and identified the fish species that call White Ring home. Most importantly, we've learned the cycle of this blue hole.
Ocean blue holes alternately blow water out (spring) and suck water in (siphon) as the tides fluctuate. In some cases, the spring cycle is strong enough to form a noticeable slick or boil on the surface, giving rise to the often-used term of "boiling holes". During the siphon cycle, water is sucked back into the cave and can be dramatic enough to form a whirlpool on the surface. As the hole transitions or "turns" between springing and siphoning, or vice-versa, there is a brief slack period where there is no flow at all.
Many factors affect the cycle of a blue hole. The tide cycle being the most important, but the size of the cave, the number of entrances, and even the wind plays a part. Each blue hole is unique and its particular timing must be verified over several days to safely begin diving.
Ideally, dives start at the end of the siphon and continue as the blue hole begins to spring outward. Dives can also be safely made at the end of the spring cycle as long as the exit is made during the slack period, before the cave begins to siphon. The most dangerous time to start a dive is when the system begins to siphon. A diver caught in a siphon can use considerably more air to get out than it took to get in and if unprepared for this, could very easily run out before he or she is able to exit the cave. Special air rules are used by trained divers to safely dive a siphon.
Cave diver's use the "rule of thirds" to plan their dives. One third of their air is used going in, one-third coming out, and one-third is held in reserve for emergencies. This means that if one member of a buddy team loses all of his air at the furthest point in the dive, there is still enough air in the other divers tanks to get them both back to the surface. However, there are many situations, and diving in a siphon is one, where more conservative air rules are required. A diver may elect to use only one-fourth or one sixth of his available gas supply on the way in to allow a safe exit with enough gas left for emergencies.
Tom and I know from previous dives that White Ring will spring for five hours before going slack. The slack period only lasts twenty minutes before it will begin siphoning. In another ten minutes it will be at full flow and extremely difficult to make any headway against the current. We know that we don't want to be in the cave when this happens and we plan accordingly. We determine a time that will put us in the cave about forty-five minutes before the slack period begins. There will be considerable flow against us as we go in, so we plan to use Diver Propulsion Vehicles (DPV's or "scooters") to assist us in swimming against the current.
If our dive goes according to plan, we will exit in the slack period. Should anything go wrong, or even if one of us just doesn't feel right about the dive, we will call the dive and exit the cave. One of the cardinal rules of cave diving is that anyone can "call a dive", meaning to end the dive immediately and exit the cave, at any time for any reason. Sometimes it can be as simple as not being mentally prepared for the dive. This initial sense of unease, coupled with a real emergency in the far reaches of a cave, could spell disaster for the diver and his buddy. Smart cave divers recognize and listen to that little voice in your head that says, "you shouldn't be here today".
In the meantime, the voice in my head says I need a nap. The dive is almost three hours away, the compressor has another hour to go, and the lunch dishes are washed and put away. The boat rocking in the gentle swells of the Caribbean Sea, combined with the warm sun and the slapping of the waves against the hull, conspires against me as I drift off to sleep.
A sudden silence awakes me as the compressor shuts off. I'm uncomfortable now in the heat, the vinyl seats are stuck to my back, my limbs feel like lead and I lay in this uncomfortable state, waiting for the heavy blanket of sleep to lift. Tom is still asleep on the other side of the boat and Sandra is catching some sun up front. I struggle up to my feet and fall off the back of the boat, the cool waters clearing my head as I swim over the top of the hole. I can feel the temperature change as I move into the boil from the cave. White Ring is still blowing strong, but it won't be long before its time to dive.
I climb back on the boat and Tom and Sandra are beginning to move around. Tom is unhooking the filling manifold from the tanks. I remember that we haven't spooled any line for this dive so I collect a couple of reels and a large spool of nylon line.
As we explore the cave, we put in a continuous nylon guideline to show us the way out. Most of the time we use a small braided nylon line, braided because it doesn't wear through as easily as the twisted nylon line commonly sold in hardware stores. White Ring presents a unique challenge because this cave has a lot of coral, which is very sharp and abrasive. The small braided line is quickly worn through by the jagged rocks, which act like a knife-edge, as it vibrates in the high water flow. Therefore, we use a thick parachute cord for our exploration. This parachute cord is made of a thick nylon line inside of a nylon jacket that gives it additional protection the coral rock.
The primary purpose of the guideline is to show us the way out of the cave. To help in identifying the correct route, directional arrows, known as "Dorf" markers, (named after their originator Lewis Holtzendorff) or simply "line arrows", are periodically placed on the line to point the way to the nearest exit. We are extremely careful to always maintain awareness of where the line is in case of an emergency. Should we lose the ability to see in the cave, due to stirring up the fine sediments on the floor of the cave, or in the unlikely event of losing all lights, we can still follow the guideline by feel back to the entrance. This skill is so important that we practice it from time to time to make sure that we can do it when the time comes. The "line arrows", which are easily recognized by feel in the dark, also provide reassurance that we are traveling in the right direction.
A secondary purpose of the line is to measure the distance in the initial exploration. Knots are tied in the line every ten feet and by counting the knots while swimming out, we can measure the distance into the cave. If compass bearings are taken where the line changes direction, a map can be drawn showing where the cave passage is headed. Additional information, such as the distance to the walls, floor and ceiling, and notable features of the cave, like placement of rocks, ledges, and pits, allows the mapmaker or cartographer to draw an accurate view of the cave. The resulting map can then be used by other divers or by researchers studying the cave.
Sandra and I start by marking off ten feet on the deck of the boat. I take the spool of line and tie a knot near the end. Sandra begins winding the line onto the reel, and when she comes to my knot, she lays it on the ten-foot mark on the boat. I then pull the line tight, tie another knot, and Sandra reels in the line to the next knot. We continue this way until we have knotted up about 800 feet of line. This should be plenty of line for our dive today.
As Tom and I begin assembling our equipment, Sandra puts on her dive gear and takes two bottles of oxygen into the water. These will be used at the end of the dive for decompression. Because of the time spent and the depth of the water, our bodies will absorb much more nitrogen than normal. We must get rid of the excess before we can surface or we risk getting decompression sickness, or "the bends". The oxygen helps us to get rid of the nitrogen faster and makes the decompression safer, but we have to be sure that we are no deeper than twenty feet while breathing it. Below twenty feet, the oxygen becomes toxic and could cause a seizure.
Sandra will clip the oxygen bottles off to a line placed in the water for this purpose. We don't want them to inadvertently float off. As Tom and I exit the cave we will pick the bottles up and begin breathing the oxygen at twenty feet.
By now our dive time is rapidly approaching. Things are quiet as Tom and I put on our wetsuits. Sandra returns as I slip into my buoyancy compensator. She gets out of her gear and does a quick run down of the check off sheet: dive computer, survey tools, back-up lights, safety reel, exploration reel, mask, fins, and air is on. She helps me clip off one of my sidemounted bottles before I jump in the water. Once in, she hands me the second bottle and I clip it into my harness. Still floating on the surface, I check that both regulators are working properly. That done, I make sure that the hoses are routed so that I can easily switch between the two tanks, and that I can hand off my long hose in the event that Tom should need it. I also check that all hoses are properly stowed so that they don't catch on outcroppings or drag, possibly causing damage to the cave.
Last, Sandra hands me a stage bottle. A stage bottle is an extra tank carried by the diver to go further in the cave. The same air rules apply to stage bottles: one third is used going in, one-third for exit, and one-third for a safety margin in case of emergency. The tank is fitted with brass clips at the bottom and top of the bottle to clip into the sidemount harness.
Tom is now in the water, stowing gear and going through the same pre-dive check. I watch, checking over his gear, looking for anything that looks out of place, anything that could cause a problem once we are in the cave. Tom finishes and begins to swim towards me. He is also checking my equipment, double-checking that all looks well before we start the dive. He gives an OK signal, which I return, and we head towards the entrance of the cave.
We pass over the white sand and sea-grass beds in the shallow waters surrounding the sink. A startled stingray rises out the sand and slowly glides a few yards away to bury himself again in the sand. Several Mutton Snappers eye us from a distance as we pass.
We begin our descent, the water welling up from the cave buoying us upward as we drop over the limestone edge. We pass by a school of young barracudas swimming in formation, their noses all pointed towards the cave, into the flow. The walls turn deeper and deeper shades of blue as the depth filters the sunlight. The dark entrance to the cave slowly begins to take shape.
The full force of the current catches us as we reach the entrance, blowing us toward the opposite wall. We instinctively head into the flow, the vibrant reds and yellows of the encrusting sponges leap out at us as we turn on our primary lights. We start our DPV's, the engines emitting a high-pitched whine as we begin our journey into White Ring Blue Hole.
We pass under the edge of the cavern, seeing nothing but blackness beyond. Our dive lights, as powerful as they are, seem weak compared to the sunlit sink behind us, but the cave slowly begins to take shape as our eyes adjust to the darkness. My light illuminates a group of three French Angelfish circling on the sandy floor, confused by this intrusion into their world. A little further on, a spider crab, encircled by protective rocks, raises a claw in warning that this is his territory as we scooter past. The passage levels out, and Tom pauses briefly by a pile of boulders to check a safety bottle left for emergencies. I take the opportunity to fine tune my buoyancy and briefly check gauges. Tom signals that all is OK and begins to lead us deeper into the cave.
The flow is still very strong, I can feel it tugging at my regulator as we travel, but not as strong as on some previous dives. This worries me some, because even though we are making good time, we may have gotten in too late and the slack period will catch us before we complete our exploration. We are still safe though, we can make it out in plenty of time if it goes slack, and we will have only wasted a dive.
My thoughts come back to the dive as I see Tom signaling with his light. As I follow the beam, a five-foot nurse shark comes into view. We have disturbed its sleep and it quickly disappears further into the cave with a few flicks of its tail. While nurse sharks are rarely dangerous, I hope this one keeps going so we don't meet it in the tight quarters that I know are coming up and where it might feel more threatened.
Tom and I follow the shark down and under another ledge. We are now just over 120 feet deep and over 500 feet into the cave. I see the nurse shark still leading us in and watch as it deftly slides into a side passage. As I go by I probe the dark passage with my light. The nurse shark is nowhere to be seen, but I can see the silt he stirred up being sucked into the passage. This reminds me of a still unexplored lead near the entrance to the cave that heads in this direction. My guess is that this is where that passage connects to the rest of the cave, but that is another dive.
The passage is getting larger now, probably 40 to fifty feet wide. The middle of the cave is split by a fracture that rise twenty to thirty feet above the floor and is fifteen feet wide at the base. The sides taper off to five or six feet high at the edges. Large blocks of limestone that fell from the ceiling many eons ago give the illusion of traveling through a boulder choked streambed in some narrow Western canyon, except for the occasional lobster skittering along the walls. Red and yellow sponges still cover the walls and rocks, and we occasionally see a large black sponge. Tom points to a beautiful stone crab hiding under a ledge, the brilliant reds and blacks on his shell shine in powerful illumination of the 50-watt light.
The line takes a hard left along a ledge rising out of the floor. We can see the passage continues forward, but becomes much lower. The water seems clearer back here as we follow the fracture in the ceiling to the left, which makes for easier traveling. I can see passage continuing straight ahead, but the line turns right again and into the main water flow. We have now hit the deepest section of the cave so far: 137 feet. The passage has also gotten steadily wider, but the numerous columns supporting the ceiling make it difficult to determine the true width. We estimate it is around 100 feet wide at this point. The floor is no longer as sandy, and is comprised mostly of old shells and rocks that presumably have dissolved out of the limestone. The ceiling fracture is still present, but not as impressive as it was earlier.
I check the pressure on my stage bottle and note I am getting close to thirds. We are also approaching the end of the line. I am thinking that we timed this dive almost perfectly. The last time we dove this tunnel we had to grovel on the floor and pull against any available rock to make any headway against the flow. Even while using the scooters, we had to also swim hard to make any headway. Today, while the flow is still strong, the scooters are able to overcome it and we've made excellent time.
I see Tom stop as the end of the line comes into view and I switch from my stage bottle regulator to my right side tank. I stow the stage regulator in rubber bands on the tank for that purpose, turn the bottle off, unclip it from my harness and clip it to the line. I take one wrap of line around the clip so the current doesn't carry the bottle off. Next, I do the same with the scooter and leave it next to the stage bottle. I reach behind me for the exploration reel. Tom holds a loop tied, for just this purpose, in the old end of the line and I pass the new line through and pull it tight. We double check that both knots are well secured before continuing; this is no place for a knot to come undone. I can feel the adrenaline start as I give Tom the OK signal. We point our lights into the flow and start to explore virgin cave.
The passage is sloping up and appears to be heading left. The ceiling is still high underneath the fracture, but there is a very low, undercut section near the floor. The way the passage curves makes it very easy for the line to drift into this section, creating what we call a "line-trap". A diver trying to swim through this low section would have a very hard time, especially in the reduced visibility conditions that usually accompany an exit. Recognizing this, I find a suitable rock and secure the line to one corner to keep the line in the main passage. We continue down the passage like this, heading into the flow, searching for good places to secure the line, our lights probing the darkness, first right, then left, trying to take in as much of this cave as possible in the short period of time we have.
We come to a huge boulder blocking the passage and the ceiling fracture seems to have disappeared. The cave taunts us with glimpses of white sand floor rippled by the flow as we peer around the boulder. I look down at the reel, there is still some line, but not much. Our air is getting close to thirds also, and while we could continue further, we still have to survey on the way out. As much as I want to see what is around this boulder, common sense tells me this is a good turning point and we can negotiate a way around the boulder next time when we have plenty of air. I look at Tom and can see he is thinking the same thing. I reluctantly wave my finger in a circle, the signal to turn around, and Tom returns the signal to show his agreement.
I see a rock on the floor, right next to a patch of brilliant orange staghorn sponge. It seems odd to see such bright colors this far back in a cave. I wrap the line around the rock and hold the reel up while Tom cuts the line. He takes the reel while I finish securing the line to the rock. As a final touch, I make sure to tie a bowline loop in the end for the next exploration.
As we turn to begin the exit, the visibility, which was over 100 feet coming in, is now reduced to less than five feet by the bubbles from our exhaust knocking sediments off the ceiling. The flow is much less now and I realize the slack period is approaching rapidly. Another good reason to turn this dive now.
We still have to survey the line for our map, so I dig my compass, pencil, and wet-notes out and I begin the familiar routine of collecting depth, direction, distance and sidewalls as we begin swimming out. By the time we reach our scooters and stage bottles, the flow has carried off some of the debris we stirred up and visibility is starting to clear. I put away my survey tools and clip on the stage and scooter and Tom and I begin the ride out.
We meet up with the nurse shark again near the entrance. It has found a friend, a little three foot nurse shark. Not liking our company, they bolt towards the entrance and the open water. We can feel the flow of the blue hole gently starting inward. Our dive was perfectly timed.
We slowly begin our ascent to the surface. The fish are not as plentiful as before the dive. Nearly all of them have moved away from the entrance and the pull of the water now entering the cave. At twenty feet we stop and begin decompressing using the oxygen Sandra placed there earlier.
Tom and I have about forty minutes to decompress before we can surface. The time goes by slowly, Sandra comes by to check on us, making sure that we are OK. We rest on the bottom, near the edge of the sink, watching the snapper swim lazily along the bottom, each thinking our own thoughts. For now, our exploration is over. We've accomplished a lot on this trip, but there is still much to do. We know the cave continues, but how far, we still have to discover.
Our thanks to the following for their help and support. We couldn't have done it without them:
Judd and Dale Rosen, Jim and Barbara Sweeney, and Janine Turner. Thanks to American Underwater Lighting for their assistance with video lighting.