The body of 30 year old Jordan William Scott was discovered at Ratchaprapa Dam in Khao Sok national park at 19.50 on Monday evening.
It was previously reported that Scott had been on a day trip to the Ratchaprapa Dam last Friday with his girlfriend and other friends.
He was playing in the water normally before midday then got out and jumped in and could not be located.
The American Embassy has been informed.
Spring News reported that officials will meet with local boat and houseboat operators at the dam to ensure that safety requirements are being adhered to.