Police identified the dead man, brought back to shore by lifeguards from Patong on a jet-ski and a speedboat, at Yoshiaki Hirose, 48.
While all options are still open, the initial belief of police is that he may have chosen Valentine's Day to end it all for reasons that have yet to be disclosed.
His body appeared to be weighted down with rocks.
Mr Hirose left his shoes and clothes in a neat pile on the rocks above, which is what initially alerted passersby and led to a more thorough search of the waters off the rocks.
His body was taken to Patong Hospital.