The man, whose name The Phuket News is withholding until his family have been informed, was pronounced dead at Patong Hospital when transferred there after being pulled unconscious from the water at Karon Beach at just after 2pm.
A Marine Safety Unit based at the Tourist Information Centre of Karon Beach were informed about the incident at 2:20 pm.
Members of the unit performed cardiopulmonary resuscitation (CPR) on the man prior to him being taken to Patong Hospital, where he was pronounced dead.
The British Consulate in Phuket has been notified of the death.