A British woman has died and a British man is believed to be missing after a speedboat capsized in Thailand.
Another British national was injured in the accident near the popular tourist island of Koh Samui on Thursday, the Foreign Office said.
Thai tourist police said 32 passengers and four crew were on board the Ang Thong Explorer boat which was travelling from Mu Ko Ang Thong National Park when it hit a "big wave" and capsized at 5pm local time (11am BST).
A second woman from Hong Kong also died, while a German woman is also missing, police added.
A senior police spokesman told the Press Association: "We're still trying to check everyone. One British woman has died and one from Hong Kong. Two people are missing."
He added that the bodies of the two women have been recovered from the sea.
A spokeswoman for the Foreign Office (FCO) said: "We are supporting the family of a British woman who has sadly died following a boat accident near Koh Samui, Thailand.
"Another British national has received treatment in hospital for injuries suffered in the same incident.
"We remain in contact with local authorities in Thailand for further information."
The FCO could not confirm whether a British man was also missing.
It is believed there were other British people on board the boat but they are understood to have been released from hospital following treatment for any injuries they sustained.
Koh Samui is among the most popular Thai island destinations for backpackers and luxury holidaymakers alike, and is known for its beautiful beaches, coconut plantations and waterfalls.