Capt Prasert Thongprom of the Kamala Police was notified of the man’s death at about 3am.
Police arrived to find the body of Chinese national Dong Jian by the hotel pool, reported Capt Prasert.
Police did not name the hotel.
“We found no marks or wounds on his body,” Capt Prasert said.
“His friends told us that Mr Dong and nine of his tour group went out for dinner at a nearby restaurant the night before, where Mr Dong drank two large bottles of beer,” he added.
Mr Dong returned to the hotel at about 2:40am, and changed to go for a late-night swim in the hotel pool.
“His friends arrived and found him floating unconscious in the water. They pulled him out of the pool and began CPR, but Mr Dong failed to respond,” Capt Prasert said.
Emergency workers soon arrived, but also failed to resuscitate Mr Dong, he added.
“His friends explained that Mr Dong had a heart condition and recently received hospital treatment in China before coming to Phuket on holiday,” Capt Prasert said.
“We believe that the alcohol might have affected his system, causing him to drown, but we have had his body taken to hospital for further medical examination before close the case,” Capt Prasert said.