Scuba diver Man Panwan, 46, of Kanchanaburi municipality, ascended too quickly, then complained of severe pain in his neck and lost consciousness.
Mr Man was given first aid and taken to Tha Kradan Hospital in Si Sawat district, taken to Paholpolpayuhasena Hospital in Muang Kanchanaburi district, and then Somdech Phra Pinklao Hospital in Bangkok, where he was declared dead from an air embolism.
Mr Man was among a large group of divers and rescuers who joined the search for Anirut Khunwijaeng, 39 of Bangkok, who fell from a tourist raft on the reservoir last Saturday (Oct 8) and has not been seen since.
The search of the 12.8 billion cubic metres of water behind the dam entered its fifth day yesterday, and was being hampered by the many submerged trees and other obstacles. Visibility underwater was down to one metre.
Mr Anirut and his wife were on a rafting trip.
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