The Bangkok Post and the Chiangrai Times say the man has been identified by his Thai girlfriend as Jean Caroche.
The newspapers report that police found Caroche on Thursday floating face down in the water off Koh Lan, an island near the resort town of Pattaya.
It says his girlfriend Alusa Sondee, 31, told police he rented a boat in Pattaya on Tuesday but never returned to shore.
Police have reportedly contacted Canadian authorities.
The Department of Foreign Affairs could not immediately be reached for comment.
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