Return to Mount Carmel – my first Trimix dive
In fact only about a month later we were back to assist Nuno in his quest to explore the cave. Given our recent deep diving we felt we could go deeper faster so this time our first dive was to forty metres. As before each dive had an objective and as before we got to place the oxygen in the crack on our way down. My second dive was down to 50 metres and we placed more stages on the line. As on all my other trips the visibility was breathtaking. The cave really started to expand from forty metres on down. Next day saw Ian and Nuno do a work up dive to 100 metres. This dive served as a dry run for Nuno’s even deeper push later in the trip. Everyone was to do the same thing on this dive as on the big day.
One thing that I got used to on these trips was doing solo support dives. We tried to ensure that the deep divers were pretty much covered their whole dive, and that meant we needed to overlap the support divers. For example if Craig was to meet Nuno and Ian at 50 metres and stay with them till they reached thirty, I might meet them at forty and stay with them till twenty. You can see that even though we had no ‘buddy’ per se, we were seldom far from other divers. Another technique we developed was to meet the deep divers and once we established they were doing well, the support diver would move up a few metres and so hang close by and ready to help at a moments notice, but out of the way. This technique meant that we did not incur as much decompression as if we’d stayed at the maximum depth for as long as possible. The 100 meter dive went well and both deep divers surfaced in good condition.
As on the previous trip, the next day was a rest day for Nuno and Ian, which meant the rest of the team could do some exploratory dives. Craig and I did another 60 metre exploration and once again I tied off and swam off the main line. We found another corner which begged for exploration, but unfortunately given our limited gas supply we had to turn back to the main line.
Whilst the team was doing these dives, Nuno and Ian were very busy mixing the gases for Nuno’s push the next day. That evening he announced to the team that his target was 154 metres. Ian was to be deep cover at 100 metres. This dive was Nuno’s deepest and longest dive to date. I think the dive took over five hours to complete. One thing I remember is that Nuno surfaced from that dive quite tired. Very wary of the potential for the decompression illness that heavy exertion after such a deep dive can bring on, Nuno stayed at the bottom of the hole for some hours and made a point of drinking warm drinks and not moving more than he absolutely had to. Only then did he slowly make his way up to the camp site. Even then we made a point of observing him and making sure he had enough fluids and exhibited no signs or symptoms of decompression illness. As it turned out the fatigue was all we saw and everyone went to bed that night very relieved and pretty exhausted.
The next day Nuno and Ian rested again and we had another day to do personal dives and clear out the cave. My final dive of the trip was not only another depth milestone for me but also my first Trimix Dive. Nuno put together a dive plan for Craig and I. Our maximum depth would be 76 metres. As usual, we’d have to retrieve some of the deeper stages from the previous dive as well.
Looking back on the kit I used, I chuckle to myself. I don’t think I’d be very happy to let anyone do it today. I had a jacket BC with a twelve litre steel tank on my back and a twin six litre set clipped to my front containing my Trimix. So in the modern jargon my travel mix was air and my bottom mix Trimix. Like all the other dives we dropped down the line and came to hover at 76 metres with inky blackness below us. I thought to myself that this was an incredible feeling, to be this deep and not feel any of the telltale signs of narcosis I was used to dealing with diving on air. Our equivalent air depth was around forty metres. I felt much more in control. As expected I was thinking more clearly that I had on our earlier deep air dives. As we waited for our bottom time to run out I made a point of checking my gauges and communicating via hand signals with Craig. Eventually we gave each other the thumb up signal to begin our ascent.
It had been arranged that whilst the rest of the team continued to clear the shallow stages out of the cave, we would retrieve a deeper stage each from the line. By the time we got to our fifteen metre stop the surface oxygen supply was out and we had to use the back-up oxygen cylinders to decompress. Instead of the usual comfortable surface supplied oxygen we had to manage an extra cylinder each. I can hear the shouts of disbelief echo around the world. Fifteen metres on pure oxygen! That’s 2.5 bar (or just about, given that we were diving at an altitude of over 1500 feet), it’s not safe, it can’t be done! Well we didn’t know any better and I guess we were just plain lucky that no one got oxygen seizures or worse. No one would suggest using oxygen that deep nowadays. I wouldn’t think of using oxygen below six metres. We were however not totally ignorant of the dangers of breathing pure oxygen for prolonged periods and so we broke up the oxygen with air. A technique now very common on long oxygen decompression stops. Over the years I’ve learned to position my stages in such a way that I can do the required long decompressions in relative comfort. Back then I was still new to it all. Although I really enjoyed the dive and the clarity the Trimix afforded me, I struggled with the long and cold decompression. I think I resolved on that very first long, cold dive, to get myself a dry-suit as soon as I could. Craig and I literally shivered through the last half an hour.
I also learned an important lesson during that dive. Everything had gone like clock-work, until suddenly, during our decompression around the twenty metre mark, I felt my helmet was drifting off my head. I should point out that my helmet carried four of my six torches and enabled me to work with both hands as necessary. Without if we’d be down to Craig’s lights and my two hand helds. I quickly reached up and caught the helmet before it could go too far. Feeling very happy with myself, I grinned at Craig, then, foolishly, slung it over my arm. Of course the moment we moved up to the next stop I got busy with depth and time readings and the helmet slipped off my arm. I realised just in time to see it tumbling off into the depths. For a moment I was stunned. How could I have been so stupid? There was nothing for it but to continue our decompression and forget the helmet. I’d more or less accepted that I’d lost the helmet when Nuno came down to check on us and of course asked (by writing a question on my arm slate) where my helmet was. I shrugged and pointed down. He gave the ‘okay’ signal and disappeared down the line. A few minutes later Nuno reappeared. He was beaming through his mask and holding my helmet in his hand. He’d also clipped it onto his harness, just in case. Thanks to Nuno I still have that helmet almost twelve years later. I even dive with it occasionally.
The decompression schedule we did back then
Depth in metres
Time in minutes
Gas breathed
36
3
Air – changed to HeliAir 50:50
75
10
HeliAir 50:50
36
1
Changed back top Air
18
7
Air
15
20/20
Oxygen/Air in 5minute intervals
12
15/15
Oxygen/Air in 5minute intervals
9
4
Oxygen
6
12
Oxygen
3
24
Oxygen
131
Total Time
Impressions of infinity-100 metres and beyond
The following year, 1994, we were back at Boesmansgat in February. Nuno wanted to attempt a dive to 220 metres, an African Record at the time and very much at the edge of technical deep diving. By doing a sub-200 metre dive Nuno would be joining an elite of only a handful of divers in the world. Everything about dives by scuba divers to this depth was really unsettled. Even now scuba dives in this range are extremely rare. I reckon the number done in any year can easily be counted on one hand. This trip has a personal significanc
e for me, as I finally achieved what to some people is the holy grail of deep diving; I reached the magical depth of 100 metres. Once I had done this dive, in this place, I felt I had been well and truly accepted into the deep diving fraternity at Wits.
I remember arriving at the water’s edge. Everyone was eager to be the first to see what the visibility was like on the surface. This time we were standing in a drizzling rain, contemplating a pool of dirty brown water. We had no idea what the lower reaches of the cave would turn out to be. At that point we did not even know if we’d be able to dive, let alone if Nuno could make his big push. To do a dive as complex as the one Nuno was contemplating in low or no visibility would add to the already high risk in a way that none of the team felt really confident with. We resolved to have a look below the surface and see how deep the murky water went. I can’t recall who got that first dive, but they came back up happy to report that it was pretty clear below thirty metres (this is a sinkhole so there is very little if any current in the water). With luck by the time we got the cave rigged with spare cylinders and shot lines it would have settled enough for us to safely manage Nuno’s long decompression.
My first few dives were as per usual; first dive to forty metres to check all the equipment still working. I remember it felt strange to dive down through a misty brown haze where just last month it’d been crystal clear water. The mist only began to lift around thirty metres, by forty we were back in clear space. My second dive was a pretty deep 60 metres on air. Although I’d done this dive before, I recall that this was one time when I felt the effects of narcosis a little more. Maybe we descended a little too fast, or it was a little colder than before, but as we went past 50 metres I felt a kind of woolly feeling come over my thinking. Experience had taught me what this was. I was under the influence of nitrogen narcosis. I did what I always do when I feel this happening; slowed down my descent and consciously took a few deep slow breaths, in … out … in … out. As my head cleared I noticed my compass had slipped down over my watch and was hanging around my hand. There at 50 odd metres I moved it back up my left arm and carefully tightened the strap. My thinking had cleared up. Once again as I’d seen before, nothing like concentration to clear up the narcs! The rest of the dive went very well. By the end of that day the cave was ready for the really deep diving to start. Among them would be my first 100 metre dive. This major milestone dive was a real eye opener for both Craig Newham, my buddy once again, and myself. Deep diving techniques and methodology came together. Once more we headed down through the crack. This time we had twin tanks of Trimix on our backs and stage cylinders of Nitrox clipped onto our harnesses for decompression. We followed the line down the wall, past the back-up oxygen cylinders and surface supply oxygen line. Our lights picked up small puffs of silt where our fins touched the wall. Looking at the ledges as we drifted deeper and deeper I saw heaps of silt just waiting to be stirred up. We were very careful and nothing much got stirred. Visibility was by now excellent again. As we moved deeper I was conscious of the walls moving farther and farther away from the line. We were moving into the vast open space of Boesmansgat. At 50 metres we changed over to Trimix. We paused for a moment to check on each other. We exchanged ‘okay’ signals and continued our descent. Finally we reached the 60 metre ledge. This is the point Nuno had warned us about, deeper than this, given our current torches, the walls were no longer visible. We plunged on into the abyss.
No bottom was visible now either. The only visual references I had were the shot line, my buddy and my instruments. I made a point of looking up - nothing. Down - nothing. Left and right - nothing. We carried on down the line, our depth gauges inexorably ticking over 70 metres, 80 metres, and then 90 metres. All the while I periodically injected air into my BC - I really didn’t want to overshoot my target depth here. Finally my depth gauge read 101.4 metres. I remember thinking “I guess that’s close enough”. Craig and I shook hands and I could see him grinning through his mask. The water at this depth was literally as clear as the air on a clear spring Karoo evening, and I was struck by the similarity of our experience to that of an astronaut as he walks in space, so far above the earth. The only difference was that we gazed out from our shot-line moon base into a starless sky.
All too soon our time was up and we had to begin our long patient ascent to the surface. If we hadn’t left the 100 metre mark then we would run the risk of not having enough gas to finish the dive. Even though we had planned for extra gas, we started up. We had no desire to test our emergency plans. We were met on the way up by Liz and Verna this time. It’s always nice to see your friends again after these dives. One sort of feels you’re safe. If all has gone as planned then one feels like the first dangerous phase of the dive is past. Now all that’s needed is patience and concentration on your decompression schedule. Of course there is no guarantee that you’ll be free of decompression illness. We all know the condition can manifest at anytime during a dive or even many hours after the dive. Still, we were out of the extreme deep zone.
Because of our Trimix dive, the next day was a rest day for Craig and I, but I was allowed to do one very shallow dive. It was very unusual in that I decided to take only minimal equipment since it would only be about a five minute total dive time. I took no torches, relying instead on natural light and even went in my speedo costume. My task was to go through the first entrance slot to put stage bottles and drop weights in place for Nuno. The drop-off point was just below the crack at about 6 metres. Whilst it was very close to the entrance and I had three ways out of the cave, it was still in the cave. It was a very, very, peaceful dive. In between the noise of my exhaust bubbles I was in complete silence, with only soft light sneaking around the big rock that blocks the entrance. Once my eyes had adapted to the half light I could see quite well. I looked up through the crack and marvelled that I could clearly see up through the water and into the clear sky above it. After only a few minutes I felt a shiver, cold again, time to get out. Well that was that, one of the shortest dives ever done at Boesmansgat.
Craig Newham and Myself decompressing during my first Trimix dive to 76 metres dive at Boesmansgat. Note the jacket BC’s and slung twin sets.
After almost a week of ever deeper diving everything was ready for Nuno’s deepest ever dive. For the big dive I would be deep air support at 65 metres. Besides checking on Nuno’s physical condition, my job would be to retrieve Nuno’s deep set of twin ten litre tanks as well as a single six litre steel cylinder that he no longer needed. I met Nuno on time and he was doing fine. He reached down and unclipped the six litre and handed it to me. That went fine. So when he repeated the process with the set of twin tanks I took them without thinking about it. It was a mistake that could have been fatal. Immediately I felt myself dropping away from him. I grabbed my power inflator with one hand and the main line with the other. I was just able to hold on long enough to get enough air into by BC to stop my descent. I’d dropped about five metres. I looked up at Nuno and signalled that I was okay. After another brief check on him to see if he wanted me to bring anything back on my next session with him, I headed up to the surface. I think I surfaced this time with four stage bottles. It’s not easy to squeeze back through the crack that loaded. I had to proceed carefully and ignore the odd boing, boing, scrape as the tanks bumped against the side of the chimney, but I got out. Thinking about it afterwards I had a sobering thought. Divers had died in situations where their BC could not cope with the rate at which they were descending. They simply continued to drop until they passed out from narcosis and drowned. I’d been fortunate in that I’d reacted appropriately and I had a BC that could actually cope with the load. Also, I’d been trained to keep my BC trimmed at all times, not virtually empty as some divers do. All it took was a small adjustment to stop my drop. If I hadn’t done that I might not be writing this book now.
The expedition was a success for us and we all left Boesmansgat that year feeling that we’d added a small chapter to the story of deep cave expl
oration. Then in April something happened that caused me to think about our diving in something of a different light. Up till that point I guess I’d subconsciously felt that since Nuno was not diving deeper than other people like Sheck Exley, the danger was somehow manageable. We were not doing anything that others had done before us and survived. Not always unscathed, but alive. I don’t think anyone on these expeditions ever really thought about how close Nuno was going to the edge. Until, April of 1994, when during an attempt to reach 300 metres in Xacatun in Mexico, Sheck Exley died. Exley who had led the way for so long in deep cave exploration, had died in a cave. Suddenly the danger was more real, more immediate. Never mind the risk of decompression illness. If Exley could die on a dive in a cave, anyone, including my friend Nuno, could die in a cave. Nuno, who always came across as invincible, utterly sure of his plan and the attainability of his goal, was vulnerable, as were we all.
Into The Deepest And Darkest Page 5