A group of sixth-formers on a school trip to Ecuador in which a fellow student fell from a white water raft and died have returned to the UK.
Expedition organiser World Challenge has started an inquiry into the death of Matthew Hitchman, 17, from the Royal Grammar School in High Wycombe.
On Sunday he fell off the raft and attempts to rescue him "proved impossible", the school said.
The group from the school had just completed a trek to the Northern Andes.
The World Challenge trips to Ecuador generally start off from the capital Quito before moving into the mountains.
A spokesman for World Challenge, which organised the trek, told the BBC: "I can confirm that the team (which included 11 boys) has returned to the UK.
"A full independent review is already under way."
The firm had suspended white water rafting in all destinations until the completion of the review, he said.
The pupils had been working on a community project to provide sustainable tourism income in a remote area of Ecuador.
The Foreign and Commonwealth Office said: "We are supporting the family of a British student following his tragic death in Ecuador. Our staff remain in contact with the Ecuadorian authorities."
In a statement the school headmaster Philip Wayne said Matthew was "a caring, friendly and well-liked student who was highly regarded by his teachers and fellow pupils".
The school said it had focused on the "safe and compassionate return of 11 boys to the UK without one of their team mates, supporting our staff and students and giving the best possible care we can offer to a devastated family".