Incident Report

2021-08-24The diver was returning from an exploration dive beyond a 600m long and 50m (average) deep sump. The diver was using a manual CCR, carrying a suit gas bottle, spare oxygen bottle, 2 bailout stage bottles and 2 scooters (one primary and towing a back up). The diver had dropped the scooters on the way in at 48m depth just as the cave started to rise to the surface, to make the ascent cleaner with less equipment, as the scooters were not required for the ascent. The scooters were clipped to the line. On the return, the diver unclipped the scooters from the line and then onto themselves, and prepared to continue out of the cave, but had failed to properly reference the line. The diver could no longer see the line at all. The visibility was good at about a milky 6 metres but the cave passage was vast. Certain that they had not strayed very far whilst clipping on the scooters, the diver made a visual search while staying in one place. The diver was not keen on deploying a search reel owing to the amount of equipment they had about their person and was worried about the visibility deteriorating as a result of a lost line search. The diver, conscious of decompression building up while staying at depth, took a compass bearing for 'out' and made a small move forwards about 1 metre into clearer water. The line still could not be seen either ahead or behind. The diver was about to deploy a search reel when they spotted some loose line laying behind a small rock and quickly found the ongoing line, which was not well laid and quite loose. It was estimated to take about 3-4 minutes in total to relocate the line again.When stopping to do a job, always reference the line and always face it when doing a gas switch or bottle/scooter drop/pick up etc. Never turn your back on the line. Do not delay deploying and using a search reel. Always carry enough line on the search reel to cover a search pattern to suit the size of the cave passage, in this case over 20 metres would have been required. Don't allow the prospect of incurred decompression to sway you from the correct procedure. An immediate lost line search would have been quicker in this instance. By using a CCR the diver had plenty of time, but an open circuit diver would have burned a lot of gas at this depth searching for the line. Make the effort to tidy up loose line and make sure it can be seen from both directions. This line was poorly laid exploratory line at depth and was a known issue.