They and two others, who were based in Phuket, rented a boat yesterday (December 21) from the Chiewlan Municipal Pier and then dived down to a cave underwater, believed to be known as Tiger Cave.
The dead are Dmitry Dokuchaev, 46, whose body was recovered from the entrance to the cave, and Aleksander Solomatin, who managed to reach the surface and board the boat.
He was taken to Surat Thani General Hospital, where doctors decided he should be transferred to the decompression chamber at Vachira Phuket Hospital. However, he died while transport was being arranged.
A spokesman at Surat Thani Hospital said that Mr Dokuchaev was believed to have drowned, but an autopsy has yet to be performed to establish this and the proximate cause of death.
Surat Thani Vice-Governor Wichawut Jinto, who visited Mr Solomatin before his death, said, “Usually we prohibit people from diving alone without guidance in the reservoir. I will advise officials at the pier about this before they allow [boats with divers] to go out.”
First reports from within the dive community in Phuket suggested that Mr Dokuchaev may have suffered oxygen toxicity – a condition caused by a malfunction or misuse of rebreathing equipment, which can result in a seizure similar to epilepsy and loss of consciousness. Mr Solomatin apparently suffered a lung embolism.
However these scenarios have yet to be confirmed by medical experts.
Additional reporting by Alasdair Forbes