One person is believed to have gotten into difficulties at Sainoi beach about 5pm. Two others went to his assistance.
At the same beach, two rescues were carried out earlier in the day.
The dead were named at KritsadaEamkitkarn, 38, Cholamas Theerachaisuranan, 23, and Nattapong Wootapanit, 24. Their bodies were taken to Hua Hin Hospital and Bangkok Hospital Hua Hin.
Earlier, one Burmese aged 15 drowned at Nam Khem beach in Phang Nga province, north of Phuket, while his eight-year-old cousin was rescued but still in a coma late tonight.
On Phuket, there are still no lifeguards at 13 prominent tourist beaches because of a dispute about the funding process.