Two New Zealanders who were on board a speed boat with dozens of other tourists when it sank off Thailand have told of their terrifying ordeal.

The boat was carrying 37 tourists and four crew to Phuket when it sank on Monday in the Andaman Sea near the resort island of Koh Phi Phi, senior policeman Panya Chaichana said.

All 41 people aboard survived.

Navy ships, fishing boats and other vessels raced to the scene and were able to rescue everyone on board, Panya said.

William Ihaka, a 43-year-old tourist from New Zealand 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 ... 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 New Zealander, Elizabeth Hickey, 39, said she was "scared and petrified".

"We were 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, and 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."

Police said the rescued passengers were taken to both Phi Phi and Phuket islands. Among them were nationals of China, Indonesia and Malaysia.

- AP