Two boats with more than 100 passengers on board capsized and two Russians went missing off the Phuket coast.
Phuket officials said of all 138 stranded people, 89 had been rescued by the Royal Thai Navy, marine police and trawlers as of 9pm, with 49 still missing.
One of the tourists was seriously injured while nine were slightly hurt.
Phuket governor Norapat Plodthong said the Phoenix PD Diving boat with 97 people capsized off Koh Hae at 5.45pm. Forty-eight of them were rescued as of 9pm on Thursday.
At Koh Mai Ton, a yacht carrying 39 people capsized but all were later rescued, he said.
In a separate incident, a Russian couple lost contact after they drove a jet ski near Koh Racha. They were later found.
Strong winds and rough seas hit the resort island on Thursday evening.
Strong winds and rough seas hit the resort island on Thursday evening.