A whale-watching boat which sank off the Canadian coast killing five Britons was capsized by a wave, a survivor is reported to have said.
An investigation is under way into what happened to the 20-metre vessel which overturned near Vancouver Island on Sunday, leaving a woman and four men aged between 18 and 76 dead.
Some 24 passengers and three crew had been on board the Leviathan II - 21 of whom were rescued.
A 27-year-old man from Sydney is still missing, according to Australia's Department of Foreign Affairs and Trade.
The boat, operated by Jamie's Whaling Station, a local tour company, got into difficulty eight miles from the small town of Tofino.
The company's owner Jamie Bray said: "We just don't understand and we won't know the answers until the Transportation Safety Board finishes its investigations.
"This vessel has operated for 20 years with an absolutely perfect safety record - this is something totally out of the blue."
It has emerged the operator suffered another tragedy in the same spot in 1998 in which two people lost their lives.
Questioned by journalists whether the cause could be the same as the tragedy 17 years ago, Mr Bray said: "The 1998 incident happened in a totally different type of vessel that was struck by a rogue wave and the passengers were thrown out. It's a totally different scenario."
A fisherman who had rushed to the scene after the alarm was raised described seeing people in life rafts, in the water and on the rocks.
Clarence Smith said they were able to help rescue a number of people, including a pregnant woman and a woman with a broken leg.
Mr Smith said: "The lady was saying that a wave just capsized them.
"That's why there weren't any communications on the radio, no mayday."
One witness, Alec Dick, told Canadian media that a wave had "flipped their boat completely" and that he doubted people had time to put on life jackets.
Some survivors have been discharged after being briefly treated in hospital.
The TSB said the boat began to take on water around two hours and fifteen minutes after it took off on its whale watching tour.
During its investigations the team will interview crew members and passengers, examine the wreckage of the vessel, its maintenance history and how the equipment was operated, and look at meteorological conditions.
Marc Andre Poisson, of Canada's Transportation Safety Board, said was too early to say what caused the boat to capsize or what the contributing factors might be.
He said the investigation could take months.
The inquiry team will interview crew members and passengers, examine the wreckage of the vessel, its maintenance history and how the equipment was operated, and look at weather conditions.
Confirming the deaths, British Foreign Secretary Philip Hammond said: "My thoughts are with the family and friends of all those affected by this terrible accident.
"Consular staff in British Columbia are supporting the family members of those who have died and we will remain in close contact with the Canadian authorities as further information becomes available."
