Over our years of diving, our group had only three cases of minor decompression illness (DCI) or ‘the bends’. Luckily none serious enough to leave any permanent damage and only one required prolonged trips to the chamber. All we can do is analyse these incidents and hopefully learn a lesson or two for the future.
In years gone by, if a diver got bent it was generally thought that he/she must have done something stupid or reckless; in a way had ‘asked’ to get bent. Some people in truth did push their luck, but through years of investigation into decompression accidents, organisations such as DAN have found that in many of the cases of DCI in sport divers the victims had done nothing provocative. They’d dived well within the no-decompression limits of their tables and training. Interestingly, commercial divers have long held the view that DCI is almost inevitable. Its even been called a “statistical inevitability”. In recent years this ’reckless diver’ label has more or less fallen away thanks largely to the work of DAN and technical training organisations which have been more open with their incident figures. I think this is a good thing because more people are willing to call DAN for help. DAN has accumulated much evidence which clearly shows that the sooner barotrauma injuries are treated, the more likely they can be effectively treated and the more likely the person is to be able to return to diving.
Part of the reason for this book is to show the reader what worked and continues to work for us on actual dives, not theoretical notions of what should work most of the time. I don’t mean to imply that other groups of cave/deep/technical divers around the world are in any way less competent than us; on the contrary, we have (I hope!) learned from many of them over the years. I have personally tried to apply many techniques or procedures that have been proven to make our activity safer bearing in mind, like everywhere else in the world, our conditions are somewhat unique. I believe that everyone should be willing to learn from others, but not to follow blindly simply because of who the source may be. Furthermore I believe that as our understanding of the mechanisms of gas absorption and bubble mechanics continues to grow, our decompression models will continue to change and become safer. I hope we as a group never stop learning. I think that if we ever do, it could quite possibly be the most dangerous thing ever to happen to us.
What makes a cave diver anyway?
Cave diving has been called the world’s most dangerous activity. If one takes a minute to think about this statement, it’s not hard to see how this perception came about. A person has to have a particular character set to enjoy going into places that have no light, very little warmth, and often water so clogged with silt and mud so as to render a torch useless. At times cave divers have to squeeze their bodies into strange shapes and push their air supply in front of them. If they don’t stick to the rules formulated by divers like Sheck Exley and others, there is a distinct possibility of them not getting out of a cave system alive. Worse yet, even sticking to the rules is not a guarantee of safety.
Diving the dead-end cave
Take for example Leopard’s Cave. This is part of the Wondergat sinkhole complex located in the northwest of South Africa. Legend has it that Leopard’s Cave got its name because years ago there was a prolonged drought in the area. The drought exposed the cave to air and we were told by locals that during this time a leopard was often seen in the area (I can attest to seeing a number of Boomslang snakes, some wild dogs, a lot of unruly chickens and one very bad tempered donkey, but I never saw a leopard in the area). The water in Wondergat is ground water, and as such is subject to fluctuations that match the amount of rain the area gets in any given year. So Leopard’s Cave which is located about three to six metres below the surface of Wondergat is often not underwater. When it is, its entrance is a very narrow wedge-shaped horizontal slot. There’s only room enough for one person to squeeze into the slot and gingerly follow a line along its approximately ten metre length. Of course this means that if you get stuck you’ll have to rely on yourself to get unstuck because no one else can reach you. I remember that in places it got so tight that I could feel my stomach press on the bottom and my tanks and small 6 litre tank set scraped the roof. I can tell you that for a person used to diving in much bigger chambers this was quite a change. That was one of the longest ten metres I’ve ever swam - or rather crawled through. After what seems like the the proverbial eternity, during which I was concentrating very intensely on not getting wedged in, I became aware that the floor and the roof, which I was so close to, were simultaneously coming to an abrupt end. If I wasn’t careful I could find myself upside-down in the small round chamber than ends the passageway.
Once you get your bearings and look around slowly, you find yourself surrounded by rock. The chamber has no other way out but the way you came in. To get back out you have to negotiate the crack again and here’s the trick: because of the shape, you have to go out on the opposite side of the line you came in. If you forget, you get stuck. Quite a number of the guys in my trip forgot and had to retrace their path and try again. Quite a few were a little less full of themselves after a brief trip into Leopard’s Cave!
But this is my point; why would anyone go underwater into an uncomfortably tight squeeze, just to get into yet another rock chamber that goes nowhere? This is the nature of the cave diver. To go somewhere just to see what is around the next corner. For us Leopard’s Cave was a training dive, we knew what we were heading into. Often cave divers have no idea what lies ahead. So what sort of person becomes a cave diver?
Speaking from my own experience, I’ve found cave divers to be very methodical people with a good amount of practical sense. I say this because in the early days of cave diving if you wanted some or other piece of equipment you had to make it yourself. Even something as fundamental to safe cave diving as a line-reel had to be manufactured at home. There simply was nowhere to buy this sort of equipment. I recall that part of my first cave diving course focused on how to build a line reel and how to waterproof torches. On a more individual level, most cave divers I know have a keen sense of wanting to explore. They are intrigued by the possibility of being the first person to see a place or find a new species. For most of the divers I’ve come into contact with, the drive to explore far outweighed the quick adrenalin rush that some people think we crave. Most of the cave diving sites I’ve dived in require quite a lot of time and effort to get to, and a lot of careful planning to dive safely. Cave divers have to think through entire dives, to try to allow for the unthinkable to happen. We need to actively consider the worst possible situations we could get into, and then of ways to get out of it. In his autobiography Caverns Measureless to Man, Sheck Exley (quite possibly the most accomplished cave diver who ever lived) relates how he used to dive caves in a state of controlled paranoia. As if the cave was out to get him (p264 Exley, 1994).
At times, to get only one or two people safely into and back out of a cave dive a whole team is necessary to carry tanks and other gear in and back out. The one thing that sets cave diving apart from other adventurous pursuits is the fact that you have only the air you are carrying with you, only the light you have between you and your buddy, only a thin line to guide you out of what can be a labyrinth of tunnels. There is a tongue in cheek saying that was often quoted to me during my earlier years as a cave diver. “There are old cave divers, and there are bold cave divers. But there are no old, bold cave divers”. It was a friendly warning not to get too zealous in my pursuit of new space or virgin caves. Still even all the planning I just mentioned is sometimes not enough. Over the years I found that cave divers need to be able to respond quickly and appropriately to the unexpected things that can and do happen on expeditions. On a number of occasions we as a team were challenged to respond in an adaptive and innovative way.
Where did that rock go?
Thinking about responding to unexpected developments, I recall an incident in 1992 that made a significant impression on me, and directly led to me buying my first diving computer. The venue for our adventure i
s called Bobbejaansgat (Baboon’s Hole). This place is about 350 kilometres northwest of Johannesburg and the nearest decompression chamber is at least 400 kilometres from the site. A group of six divers from the WUC Dive Club had gone out to Wondergat (a well known dive site near Bobbejaans) for the weekend. In these pre-DAN days, if anything happened we’d have to handle it ourselves. If transport to a chamber was necessary, we were it. At least until we hit a town with a reasonable hospital. Anyway, we always took all the precautions we could. That meant taking along a well-stocked first aid kit, portable oxygen set and spine board. In addition we were all trained rescue divers.
To help you appreciate the potentially lethal consequences of what happened that afternoon, I need to describe the site. Imagine a sink-hole four or five metres wide at the top with sheer sides, down to the water about six metres below. The rock is sort of a mixture of clay and soap stone, so not very stable; there is no current in the water, so any silt stirred up by divers or natural events like storms stays suspended in the water for quite a while (possibly days after heavy rains). This silt can reduce visibility from crystal clear to zero in literally minutes. Access to the water is via a makeshift ladder. I use the term loosely as it was actually a rusty pipe with rungs attached on alternate sides that a helpful farmer had adhered to the rock face with wire. To dive the sight you lowered your twin sets down to the water and then climbed down the ‘ladder’ and kitted up in the water. Generally a ‘twin set’ consisted of two ten or twelve litre cylinders held together by stainless steel bands, your BC, weight belt and two regulators.
We dived in pairs; it’s a good idea to have a buddy, but the cave, (especially the entrance) is not very big once you get underwater and more than four divers would undoubtedly stir up silt. In addition, two divers are a nice easy to control group. To dive the site and leave some visibility for the next pair, we would simply ride our BC down to about forty metres and then ever so gently swim either to the left or right since the cave had a vertical entrance (what climbers might call a chimney) which gradually opened up. Similarly, when ascending this we never finned; rather, just rode our BCs to the deco stops. As long as no one stirred silt, this was a great dive, especially around midday, when sun light streamed down the entrance, giving the water a spectacular bright blue hue. If you moved beyond the light into the pitch blackness of the cave and turned around you were treated to an incredible site of three shafts of blue light cutting through the water from surface to floor forty metres below.
Now, the pleasant enough pool that one climbed down into had a submerged rock about half the size of a Volkswagen beetle on which we stood whilst kitting up and waiting to dive. Craig Kahn was standing on the rock as he provided surface support for the two divers below. Suddenly, after who knows how many hundreds of years, the rock, with surprisingly little noise, slid out from under him. We could only assume it was on its way down to the cave entrance where we had two divers still underwater. As it moved it of course dislodged a mountain of silt. For the divers below, visibility instantly went from low - since it was already afternoon and the last dive of the day - to zero.
Craig and his buddy Dale immediately raised the alarm. Our group responded with remarkable speed and calmness. Craig, who had already removed his backpack and mask, quickly re-donned his tanks and helmet (with attached lights). While Dale (who’d been floating fully kitted near-by) more or less immediately descended the guide rope to check on our two friends who were as far as we knew at the bottom of the rock’s trajectory. We learned later that Dale had put his mask on whilst diving down the shot line. Hand over hand he worked his way through the brown haze. In such conditions very bright torches can work against you because the beam reflects off the mass of suspended sand particles in the water; like driving a car in mist with your bright lights on, all you see is an opaque white screen. Dale told us later that he could only use his smaller head lights. Craig was by now kitted up again and followed Dale down the line. The other Craig on the trip, who claims to this day to have a fear of heights, jumped the six metres to the water, kitted up and dived down to meet the other Craig and Dale at about twenty metres.
What Craig and Dale found to their utter relief and amazement, where two somewhat bemused divers, wondering why the visibility had gone for such a loop and surprised to be the focus of so much attention all of a sudden. To this day we have no idea where that rock went! Imagine my frustration at not being able to get in the water and help my friends, not knowing if they were dead or alive. My buddy and I had already made the long climb out of the hole and taken off all our diving kit. It would have taken us far too long to respond to be of any real help. All we could do was get a car ready to transport anybody who may be injured and then wait at the top of the hole and watch the brown water below boiling with the exhaust bubbles from the divers below. The relief of seeing our friends come safely back to the surface was something I will never forget.
As a footnote to this incident, being the last two people out, it was the job of our erstwhile divers to bring up our safety stages from the bottom. I think there was only one, but on occasion we put down two tanks. Anyway, when Craig and Dale found them at forty or so metres, one of them was trying to lift the tank, apparently oblivious to the fact that it was clipped of to an engine block or some such weight at the bottom of the permanent shot line. Who knows how long he would have continued his impossible task if the rock had not set off the rescuers to check on him. He was clearly suffering from a condition all divers know as “the narcs”. Or “raptures of the deep” as Jacques Cousteau so eloquently put it.
In deep diving, nitrogen narcosis, the narcotic effect that nitrogen has on divers, is a very real problem. Any diver who claims to be immune should be regarded with the same scepticism as a driver who says he can handle four or five beers with no effect on his ability to drive. I can’t overstate the importance of gradual workup dives and even then, extreme care should be taken when diving below forty metres (especially on compressed air, a practice generally frowned on today). In fact, I’ve often used this incident to illustrate the possible effects of nitrogen narcosis on a diver at depth. Anyway, our two intrepid rescuers duly cut the line holding the tank and assisted the other two towards the surface.
But more was yet to come. When asked, via the usual array of hand signals, at what depth they were due to decompress, one of the divers simply indicated that she had no idea and was following her buddy’s dive computer (this maybe ok on a normal recreational dive, but on a cave dive and a deep dive it was potentially very dangerous!) Anyway, we’ve all learned from it and are, I like to think more careful divers today. When I think about this dive, and how lucky we were not to have a double fatality I still get a small shiver down my spine. I have to say, our guardian angels must have been watching over us all that day. When I started this story I said it led to me buying my first decompression computer. Of all of us there (not diving at the time), only Dale had one, and as a consequence was the only one of the rescuers who really knew what his decompression was after his rescue dive. At least twice since then I’ve needed to respond to alarm calls, neither of which turned out to be anything serious, but I take comfort in knowing I have my trusty dive computer with me. In addition to being able to respond appropriately, cave divers sometimes face dangers that are unique to peculiar caves. These caves need the divers to take special precautions, and if I say so myself, at times have pretty strong nerves.
The cave with the crumbly roof
Vetsgat another very good training ground for cave diving in South Africa, is an example of a cave that has some unique characteristics. Although probably the closest cave to Johannesburg that we could dive in, it’s one of the most difficult to dive. I say this because much like many of the caves in the UK, we had to carry all our equipment underground before we could think of actually diving. So in addition to the large amount of gear we needed for cave diving, we had to take sufficient lights to last the duration of all our dives.
; The procedure for diving Vetsgat went something like this: firstly we had to get permission from the farmer who owned the land. We had to drive for about two hours till we got to a small dirt track that leads off the main highway. If a person did not know the way to the entrance to the cave I’m convinced they’d never find the place. Anyhow, once we got there we had to unload the kit from all the vehicles, and forming a human chain, pass it all down the narrow entrance into the cave. Usually we had to do this in relays as we never took more than about six people along to dive at a time because the cave is fairly small and any more would not only likely damage the cave, but stir up so much silt that diving would be impossible after only a few had dived. The cave itself had a narrow passage down which we had to lug all the tanks and kit bags and lights and anything else we wanted to use on a dive. The passage eventually opened up on a gentle slope into a large cavern, the centrepiece of which was a lake ten to twenty metres across. The water was usually crystal clear, mainly because so few people dived here. So clear in fact that on more than one occasion someone stepped into the water not realising it was there. Hence the attraction of Vetsgat for divers used to diving in relatively murky waters. Once all the kit was in the cave we could assemble all our personal stuff and decide on buddy pairs and the order of diving. Generally only two divers in the water at a time, which meant the rest of us sat about for some time in the gloomy interior of the cave. In addition to the idle chatter we had the more important task of serving as time keepers and if need be, acting as rescue divers for the people underwater. The nature of the rock that makes up the cavern made a dive in Vetsgat quite an experience, especially if it was your first dive there. We usually descended down a borehole pipe that extended through the roof of the dry space, some twenty metres above us, down into the water about ten metres. At a depth of roughly six metres we would tie our guidelines on to this pipe and then set off down a slope of about 20º. This path very soon took us under a sharply angled roof and that was when things started to happen. Because the roof and walls of this cave are a combination of clay and rock the bubbles that cascade towards the surface from divers’ exhausts valves tended to loosen bits of it, which then rain down onto the divers below. Sometimes this was just a fine brown mist, but it could as easily be individual pieces of clay.
Into The Deepest And Darkest Page 2