Survivors of a boat carrying at least two Britons which sank while travelling between islands in Indonesia swam for six hours to reach safety.
French victim Bertrand Homassel told the Daily Mail some members of the group took the life-threatening decision to swim to a nearby island.
Once there they were forced to drink their own urine and eat leaves to survive.
Mr Homassel said: "Six people were in the lifeboat. The others climbed onto the roof of the boat, which had not completely sunk.
"We waited until midday on Saturday. We were five kilometres (three miles) from the coast - there were many big waves separating us from the coast.
"People started to panic... Everyone took the decision to swim to the closest island, five kilometres away, where there was an erupting volcano."
The group were saved after attracting the attention of a passing boat on Sunday. "I was really very lucky," Mr Homassel added.
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