A French woman's body was found floating off a beach on Koh Samui in Surat Thani and a Chinese man drowned while swimming at Koh Racha in Phuket, both on Tuesday.
The 42-year-old French tourist's corpse was found floating in the sea off Ao Thongket beach in tambon Mared of Koh Samui district about 2.30pm on Tuesday, Pol Capt Waree Boonno, deputy investigation chief at Borphut, said.
Her body was brought to shore by rescue volunteers. She was wearing jean shorts and a white vest and had bruises on her forehead.
Hotel employee Suwanchai Sangkharat said hotel staff saw the body floating in the sea in front of the hotel around noon. They immediately alerted police and rescue workers, according to Thai media reports.
Shortly afterwards, a tearful French woman named only as Nathalie identified the body as that of her friend, Maud Isabeile Bailly, the reports said.
She told police the two of them had been on Koh Samui island for almost two years. Her friend was learning Thai at a language school there.
Her friend often complained about her family and health problems, Ms Nathalie said.
On Tuesday morning her friend said she was going to visit a waterfall and left on a motorcycle.
Police were investigating the cause of death.
The same day, a Chinese tourist drowned while swimming at Koh Racha in tambon Rawai of Muang district, Phuket province.
A tour guide told police that Zhu Kai, 31, had been on a day trip to the island.
After arrival at Koh Racha, he and other tourists went for a swim in the afternoon, according to Pol Lt Sakkarin Saengcharoen, duty officer at Chalong police station.
The guide said Zhu was seen struggling and he and other people went to assist him. He was unconscious when brought to shore and was given resuscitation.
The man briefly regained consciousness, but died shortly after.
His body was later taken to Vachira Phuket Hospital for a post-mortem.