The boats had gone out to sea despite a severe weather warning.

Somjing Boontham, who said he was the captain of the Phoenix, said he had urged passengers to put on life jackets while crew members frantically lowered lifeboats as huge waves slammed and tilted the boat. Pictures from the scene showed lifeboats carrying up to 20 people, some of them children.

The capsizings came as Thailand has been transfixed by the efforts to rescue 12 boys and their soccer coach from the flooded Tham Luang cave in northern Thailand.

Wang Xudong, who is with a private search-and-rescue group from China, had been assisting at the cave, but on Friday he was preparing to search for his countrymen lost at sea instead.

“I never expected to be here in Phuket for something like this,” he said. “We had good news at the cave, and I hope we can have some good news in Phuket, too. I want to help out any way I can, either for Thai people or Chinese people.”

The Chinese state news media said a total of 127 Chinese tourists were involved in the two episodes, including 37 people on one boat who worked for a furniture company in Zhejiang. Many of the tourists on the Phoenix were staying at major international resorts on Phuket.