Andrew Foch, a senior specialist for the Hyperbaric Services, participated in a technical diving expedition to the South China Sea primarily to dive several deep World War Two wrecks.
The survey showed a slight worsening of health scores during the first half of the expedition, which then returned to baseline levels. However, no diver reached a health score of a level (six) associated with clinical decompression sickness (DCS) in a previous study. No clinical DCS was detected or treated; however, a high level of pre-existing musculoskeletal complaints prevalent in this group made clinical diagnosis difficult for marginal symptoms. A high proportion (50%) of divers reported symptoms consistent with pulmonary and ocular oxygen toxicity.
The use of closed-circuit rebreathers for 74 dives in the depth range of 50 to 70 metres' sea water, with total dive time 100.4 hours, was associated with few technical problems for a suitably trained and experienced group of technical divers.
Andrew Foch's report can be found here.