The body of a foreign man was found floating off an island, about one nautical mile from Pattaya beach on Saturday, said police.
The man, whose nationality is not yet known but believed to European, was found floating face down about 100 metres off Koh Chun in Chon Buri province, said Pol Lt Sombat Kaewmoolmuk, a duty officer at Pattaya police station, who was alerted around 10am on Saturday.
Police found there were no traces of a struggle or bruises on his body. The dead man wore only swimming trunks.
The officers believed he had died at least 12 hours before his body was found. Rescue workers took the body to a speed boat heading to the shore.
The body was being kept at Bang Lamung Hospital pending transportation to Police General Hospital for a post-mortem to establish the cause of the death
Thom Yutthasunthorn, 34, a beach-chair operator on Pattaya beach, told police that the victim used the beach chair service of another operator next to his tent around Friday evening. The man then went swimming.
As the foreigner had not returned to his beach chair for several hours, the chair operator had asked Mr Thom whether he saw the man or not. Mr Thom said he did not and they assumed the foreigner might have returned to his hotel.
Police believed the man might have drowned while swimming. They had asked Pattaya hotels to check their missing guests. The officers were investigating.