The alarm was sounded by Adul Matrpanya, 33, who telephoned Kathu Police Station, which oversees the Patong district, about 3pm yesterday.
He said his ladyboy girlfriend, Nipol Jomtarak, 25, had been swept from a rock at Laem Hin Tang, a low point by the ocean on the road between Patong and Kamala.
Khun Adul told police that he and his girlfriend had been having an argument. Khun Nipol had telephoned him and asked to meet him at the spot, he said.
But as he headed towards the point where she was sitting on a large rock, a wave came and swept her away, he said.
Khun Adul was in tears when police and Kusoldharm Foundation charity rescuers answered his call.
The pair, both from Isarn, worked in Patong.
Khun Nipol's body was found near the spot about 7pm and was taken to Patong Hospital.