In April 1969, two young men dived in Kilsby's Hole, a sinkhole 20m in diameter at the surface with very clear water in excess of 60m deep. Their aim was to dive deeper than the 50m they had achieved the previous day in the same sinkhole, to carve their names on the wall. When their bubbles were no longer seen after a reasonable length of time, one of the group who remained on the surface descended and eventually saw the two bodies in a fairly deep section. The bodies were recovered later that afternoon.

The bodies were found at a depth of 45m down the side of a huge central rock collapse that lies below the entrance. It was established that they had reached a depth of at least 60m because the guideline was extended that far down, to a point where it was obvious that the divers had carried it there, and that it could not have fallen that distance. It is clear that they were returning to the surface from this great depth when things went wrong.

Both divers were badly over-weighted, a condition that leads to considerable over-exertion when returning to the surface. Although they had buoyancy vests to assist them neither was inflated, and with the stress of this effort and their great depth they would have undoubtedly suffered the worst effects of nitrogen narcosis. They also had no watches so they were unable to calculate the time they were permitted to stay on the bottom, nor the time required for decompression stops on the way up although one carried a deco meter. One diver had a twin-hose regulator, almost useless for buddy-breathing on a long return swim.

Because they did not have watches, and due also to their lack of knowledge about barotrauma and decompression sickness, they overstayed their bottom time and probably ascended holding their breath to conserve their supplies. They died from lack of air, inability to ascend due to over-weighting, and under the influence of extreme narcosis. In the Coroner's findings one month after the deaths, he stated that the two divers "had insufficient experience to dive beyond 40 to 50 feet (12-15m) together" and concluded, "I find the deaths were due to misadventure brought about by their lack of experience and insufficient training for deep diving".

Accident Analysis
Cause of Death - drowning after running out of air
Major Contributing Factors - inadequate gas for the dive, inadequate training, inadequate equipment, diving too deep on air

More information on Kilsbys Sinkhole

Kilsbys Sinkhole | Photo: Liz Rogers