60 years in a cave
The history of cave diving in Britain can almost be told in terms of the exploration of Wookey Hole, a famous cave system under the Mendip Hills of Somerset. Martyn Farr recalls the 60 years of intrepid exploration and technical advances which have taken divers to the limit of this challenging subterranean realm.
When Jack Sheppard and Graham Balcombe attended the 50th birthday celebrations of the Cave Diving Group at Wookey Hole Cave in May, their memories must have been working overtime. Displayed there were generations of diving equipment in full working order, each set of apparatus contributing to a momentous advance at Wookey or other systems beneath the Mendip Hills, home of some of the deepest caves in Britain.
Sixty years earlier sport diving had not existed, and they had been the pioneers who first ventured into those caves. Their gear had consisted of tweed clothing, felt hats and often only candles for illumination, but they had gone on to confront the most challenging barriers imaginable - the flooded sections, or sumps. Click here to see a map of the Wookey Hole Cave System.
Wookey Hole is a famous show cave lying at the southern edge of the Mendips. Here, one and a half miles from the small market town of Wells, tourists can witness the awesome power of the water which carved these tunnels millions of years ago. In this subterranean realm mysteries abound, from the infamous "Witch of Wookey Hole" - reputedly turned to stone by a young monk from Glastonbury - to deep pools of tranquil green water.
Exploration of the watery depths started here in 1935, when the Siebe Gorman company lent its "standard equipment" to the pioneers. The substantial flow of water which emerged in the show cave was known to originate well over a mile and half away, high on the Mendips, and the challenge was to follow the stream back to its source.
For Balcombe, Sheppard and Penelope Powell, the project was to be the first such attempt using commercially available diving apparatus in a British cave. Thinking of them clad in claustrophobic suits and trailing long hoses through a black, winding tunnel sends shivers up the spine.
Explorations commenced at Chamber 3, the furthest point to which the heavy surface pump could be carried. At various times there were six divers involved, and there is little doubt that all were awestruck by the experience.
"Leaving the surface and the dazzling glare of the powerful lights, and slipping down from the enveloping brown atmosphere, we suddenly entered an utterly different world, a world of green, where the water was as clear as crystal," recorded Penelope Powell.
"Imagine a green jelly, where even the shadows cast by the pale green boulders are green, but of a deeper hue; as we advanced, light green mud rose knee-high and then fell softly and gently into the profound greenness behind."
"So still, so silent, unmarked by the foot of man since the river came into being, awe-inspiring, though not terrifying, it was like being in some mighty and invisible presence, whose only indication was the saturating greenness."
The limitations of the equipment were quickly established and the task of Number 1 diver was found to be particularly arduous. He had to regulate the incoming flow of air by manipulating a pressure-release on his helmet. He then had to carry a shot-weight of more than half a hundredweight and drag along the guide-rope, besides having to haul his own airhose and telephone cable behind him. The assistance of Number 2 diver was found to be essential.. On one occasion the pump failed while Balcombe was deep in the underwater complex and he was able to reach safety only by breathing off the air remaining in his helmet and suit. But eventually Graham Balcombe and Penelope Powell covered 52m underwater to reach the isolated airspace of Chamber 7. The successful operations of 1935 clearly revealed that cave diving required the explorer to be free of all surface links.
It was World War Two that gave the impetus to developing diving equipment.
But while France saw the evolution of compressed-air apparatus, British developments were guided by the specific needs of the military. Several types of closed-circuit oxygen rebreathing apparatus appeared.
The operating principle was essentially the same in each case, with a flexible rubber hose supplying a face mask with oxygen from a breathing bag. On exhalation, carbon dioxide was removed from the gas by passing it through a canister containing soda lime.
There were, however, serious dangers in using this new equipment. Below 10 metres the diver risked sudden blackout from "oxygen poisoning", so staying shallow was vital. Water leakage into the breathing bag or mask could be similarly disastrous, as the inevitable chemical reaction with the soda lime would produce a caustic solution which would be extremely harmful if it passed into the body.
Balcombe and his friends had obtained sufficient equipment to conduct trials as early as 1942. Four years later the Cave Diving Group was founded and cave exploration entered an altogether more challenging and technical era.
It was at Wookey Hole that the usefulness of the new techniques was demonstrated. In 1947 a ninth underwater chamber was reached, 30m beyond the limit set by standard equipment 12 years previously. The following year a large, dry chamber was found just a short distance beyond. This gave explorations a serious twist. If the cave continued at a relatively shallow level, further explorations of up to a kilometre were envisaged. Such diving would obviously require meticulous preparation, because Chamber 9 was situated about 92m from base in Chamber 3. So it was proposed that Chamber 9 be made a forward base.
"The actual time taken from depot to depot will be small," said Graham Balcombe. "It is the preparations and manoeuvring on the route which take the time. There will be division of labour: divers with long-duration breathing apparatus like the 'P Party' will push ahead, while other divers explore, equip and survey the intermediate depots.
"The equipping will include the provision of a reliable telephone link to the main base, piling of gas and soda lime supplies, food spares and first aid appliances. This in turn means much work behind the scenes, waterproof and pressureproof carrying devices and a whole host of such things. Given continued access to the cave, have we the men to carry through a job like this?"
Confidence was running high but it was soon to be shaken. Late in 1948 the Admiralty Experimental Diving Unit (AEDU) took an interest in the CDG's activities, and one of those aspiring to join the group was ex-Royal Marine Gordon Marriott, who had recorded some 500 hours underwater and was an exceptionally skilful diver.
Despite limited caving experience, Marriott was invited to assist in an exploratory operation on 9 April, 1949. Four divers proceeded to Chamber 9, from where R E "Bob" Davies mounted his exploration into the unknown area upstream from the underwater Chamber 11.
All went smoothly until the exit from Chamber 9. Marriott was sent on in front but somehow lost contact with the line. When found shortly after, both his breathing bag and cylinder were empty. Artificial respiration was no use; one and a half hours later Marriott was pronounced dead.
What had occurred? Probably Marriott had let go of the line when his oxygen had expired, intending to find and operate his reserve cylinder. This was not "built in" to his breathing apparatus as required by the CDG, but tied to him by a short lanyard. When it was recovered a month later it was found to be full. He had almost certainly untied and then dropped it. In the greatly reduced visibility finding it again had been virtually impossible.
Marriott was also using fins, and while searching had presumably lost his sense of direction; by the time he managed to relocate the line it was too late to reach safety. The inquest returned a verdict of "death due to anoxaemia, accidentally sustained": cave diving had suffered its first fatality.
Weighing their actions with greater caution, the group went on working. Looming large was the serious problem of oxygen poisoning, because the further reaches of Wookey lay at greater depth. There were two courses of action. The first was to modify the oxygen principle, diluting the gas with a proportion of nitrogen to produce a mixture "safe" to greater depths. Siebe Gorman had run experiments along these lines during and after the war, but this refined apparatus was unavailable outside the naval sphere.
The second possibility was to use an aqualung, as developed by Cousteau and Gagnan in France. Bob Davies bought one in 1955, conducted his trials and began preparing to explore Wookey further. The events of the evening of 10 December are now legendary. Davies was to be accompanied by John Buxton and Oliver Wells as far as the "lip" (steep descent) in Chamber 11; it was a quarter to midnight when the team set off from Chamber 9. Buxton and Wells used the customary technique of "bottom- walking"; Davies had fins. As they gathered at the head of the final slope there was a marked drop in visibility. In the ensuing confusion Davies became detached from his friends, and, more importantly, from the outgoing line. Seeing him disappear, the bottom-walkers concluded that he must have returned to the dry cave in Chamber 9.
Davies, however, was sorting out problems with equipment, equalising the pressure in his twinset and, predictably, becoming stressed. With half his original air-supply gone, no line, and visibility down to a couple of feet, matters were becoming critical. Staying where he was, floating beneath the cave roof, meant certain death, so he started to swim in circles looking for some way out.
At the end of his third quarter of air Davies located clear water, which meant that he was further than ever from the safety of Chamber 9, and heading upstream. Then, at a depth of 15m, he saw a fissure in the roof. By now he was frantically in search of air and took a last desperate gamble. By an amazing stroke of luck he reached a small air surface. Taking off his aqualung, which was by now buoyant, he climbed up a metre or so and pulled it up behind him by one of the straps.
Buxton and Wells meanwhile made their exit from Chamber 9 to the show cave at about 3am and raised the alarm. Davies had much less than an hour's air when last seen, so his chances were not rated highly. He had realised that although Chamber 13 contained sufficient air to last several days, he would quickly succumb to cold and hunger. His air supply he estimated would last for 12min while swimming. Should he wait for rescue? Oxygen divers could not descend to 15m and in any case had no idea of his route. It would be unreasonably dangerous for naval divers to attempt a rescue using mixtures, as they had no cave-diving experience, and it could take days to instruct the cave divers in the use of oxygen-nitrogen apparatus - apart from the problem of locating him.
Davies decided to wait for about three hours in the hope that the water would clear, and then attempt to exit. Laying a line would enable him to return to the sanctuary of Chamber 13 if he ran short of air. At 3.50am he set his compass in the direction in which he assumed Chamber 9 to be, and dived. The upward slope to Chamber 11 verified his bearings and he continued.
Soon he found the line laid in 1949; here his first cylinder gave out. He was still less than halfway back to safety. Pulling on the line caused it to snap. Almost simultaneously his own reel jammed solid but he managed to detach it from his bulky, hand-held light unit just as his breathing became difficult. With only seconds of life left in his bottles he dropped the light unit and miraculously reached air in complete darkness. Davies located his emergency torch and confirmed his whereabouts. He had ample oxygen in the rebreathing set deposited in Chamber 9 on the inward journey and by 5am was back at base in Chamber 3.
"The Devil," he said, "is a gentleman."
It was a year after this lucky escape that the first mixture diving was undertaken at Wookey. During the next two years a number of operations led the divers to a constriction at a depth of 20m. In December 1960 John Buxton adopted a yet weaker oxygen-nitrogen mixture and, bottom-walking as before, became the first person to enter Chamber 15.
The early 1960s witnessed the phasing-out of closed-circuit equipment in favour of the comparatively simple aqualung. Similarly the neoprene wetsuit superseded the heavy canvas drysuit which had previously been used.
Change inevitably brought new faces to the sharp edge of exploration. In 1966 it was Dave Savage who reached the next airspace, named Chamber 18, some 123m from Chamber 9. By 1970 the modern-day trend had been set. In January of that year John Parker reached Chamber 20, the largest dry cavern in the entire cave complex. A year later the same diver discovered Chamber 22 after the (then) longest and deepest dive in the complex - 153m long and 25m deep - in the gloom of the huge Chamber 21.
It was February 1976 when the next dramatic advance was made. Within a few days first Colin Edmunds, then Geoff Yeadon and Oliver Statham and finally I advanced the cave to Chamber 25. From this point the cave went deep; first to 30m, reached in the summer of 1976, then to 45m the following year.
Once more the explorers were operating on the frontiers of diving knowledge. For the deep dive in 1977 the breathing supply was enriched with oxygen, and a supply of pure oxygen was used for decompression. Five years later the Cave Diving Group sought the assistance of the AEDU once more. To progress further in the cave entailed even greater depth, and for this an overnight camp was needed. In October 1982, supported by Rob Palmer and Rob Parker, I descended to 60m to find a low section of passage, the roof less than one foot off the sandy floor. This seemed an insurmountable barrier, but exploiting hi-tech developments Parker was to make his own mark on the cave in the summer of 1985.
Using high-pressure composite cylinders filled with trimix and special decompression tables formulated by Dr John Zummerick from the USA, the team camped for four nights in Chamber 24. On 2 July, 1985, Parker slid into the water of Chamber 25 carrying 315cu ft of gas and 40cu ft of pure oxygen in four separate bottles.
But he slid through the '82 barrier to find a further constriction ahead. At the bitter limit, a depth of 67 metres, his head was pushed into the gravel floor and he had to concede defeat. A strong current swirled menacingly in his face; the cave had thrown up a real impasse.
Ten years later divers Mike Barnes and Peter Bolt are still optimistic that further advance can be achieved at Wookey. Sixty years after those tentative operations by the standard-equipment divers, the cave has divulged relatively few of its secrets, and the Cave Diving Group continues with its quest.
As we move into the new era of the rebreather, the frontiers for the cave-diving explorer, whether at Wookey Hole, Cheddar Caves, the Bahamas or Borneo, remain as challenging as ever.
Martyn Farr is author of "The Darkness Beckons - The History and Development of Cave Diving" (Diadem Books).
Appeared in DIVER - August 1996