Mr Wei Fuo Thang, 32, got into trouble in the water just after midday on Saturday.
A representative from the Phuket Lifeguard Service said the man appeared fine after he was rescued from the water. He was responsive and assured lifeguards he was okay, but collapsed on the beach soon after. Lifeguards performed CPR, but he was pronounced dead when he arrived at Patong Hospital at around 12.40 this afternoon.
The lifeguard representative speculated that an underlying medical condition may have contributed to the man's death.
His body is now being held at Patong Hospital.