All 41 people aboard survived. The boat was carrying 37 Asian and European tourists and 4 Thai crew members when it sank in the Andaman Sea, Marine Police Lt. Col. Panya Chaichana said.
The boat was headed to Phuket island, another popular tourist destination. Navy ships, fishing boats and other nearby vessels raced to the scene and were able to rescue everyone on board, Panya said.
William Ihaka, a 43-year-old Australian tourist who was among those rescued, told The Associated Press the experience was terrifying. "The sea was very rough ... the water kept coming over the front (of) the boat, and there was so much water coming over the front that the boat started filling up with water," Ihaka said.
The crew "told us to put life jackets on, and about five minutes later, the boat sank. So we all jumped off. We were floating in the sea."
Another Australian passenger travelling with Ihaka, 39-year-old Elizabeth Hickey, said she was "scared and petrified. We were both seated at the front, and the water hit us before it hit anyone else," she said.
"We could see the waves, and we just knew that it was going to go down, we knew that the boat was going to sink." Colin Dallimors, a 48-year-old British tourist, said the first giant wave swamped the boat and stopped the engine, then another wave struck soon after, dealing a fatal blow.
"Everyone was trying to get out. The boat sank, the boat went down," Dallimors said. "I've never seen anything like that."
Thailand's Meteorological Department had predicted strong rain and high waves in the area today.
Pics: Sidharth Shukla-Rashami Desai's sizzling chemistry at TV show launch
Ooh La Lana! WWE Diva flaunts sexy curves in these 30 pictures
Photos: Salman Khan returns from Jodhpur to Mumbai
15 'peach' perfect photos of Priyanka Chopra at People's Choice Awards 2017
62 going on 16: These photos of Rekha prove she is 'forever young'