A whale watching boat which sank, killing five Britons including a teenager and a 76-year-old man, had "an absolutely perfect safety record" in its two decades at sea, the vessel's owner said.
The boat, which was carrying 27 people, capsized near Vancouver Island off the west coast of Canada on Sunday, killing a woman and four men.
Twenty one people were rescued from the stricken vessel, while one person remains missing.
Barbara McLintock, from the British Columbia coroner's office, confirmed that the British victims included three male tourists and two British nationals who lived in Canada - one woman from British Columbia and a man from Ontario.
The victims included an 18-year-old man and another man aged 76, she said.
The boat, run by Jamie's Whaling Station, a local tour company, got into difficulty eight miles from the small town of Tofino, around 150 miles west of Vancouver.
Government investigators were due to arrive in the area to begin an enquiry.
The company's owner Jamie Bray said people were "traumatised" and in "disbelief" at what had happened.
He said: "This vessel has operated for 20 years with an absolutely perfect safety record. This is something just totally out of the blue.
"We just don't understand and we won't know the answers until the Transportation Safety Board finishes their investigations."
On its website, Jamie's Whaling Station says it offers tours in Tofino and Ucluelet on "state of the art high-speed, exhilarating zodiac-style vessels" for those who crave adventure, or, it adds, who wish to "relax aboard the west coast's largest cruiser style whale watching vessels, the 65ft Leviathan II in Tofino or Lady Selkirk in Ucluelet".
The boats can hold up to 47 passengers who can "watch whales in their natural environment".
Mr Bray said passengers on boats with enclosed compartments do not wear life jackets as it could make getting out of the vessel during a sinking difficult.
"On larger vessels we're not required to have the passengers wear the life jackets. On smaller open boats they are," he said.
Video footage online showed the boat Leviathan II, bobbing vertically in the water, with what appears to be a large section of it submerged below the waves after it went down at around 4pm local time (11pm GMT) on Sunday.
The Associated Press reported that the company has suffered a previous fatal accident, with a boat capsizing in 1998, killing the captain and a tourist.
Foreign Secretary Philip Hammond said his thoughts are with the family and friends of those affected by Sunday's accident.
The Canadian prime minister-designate Justin Trudeau said he was "shocked and saddened" by the deaths, adding: "We thank all those, including our search and rescue officials, who responded swiftly with courage and professionalism.
"I know first-hand of this coastal area's natural beauty and the many people who visit here from all around the world.
"My thoughts and prayers are with the passengers, the crew, and their families at this most difficult time. We will continue to offer them support in the days ahead."
Lieutenant Paul Trenholm, from the Joint Rescue Coordination Centre in British Columbia, said people from nearby indigenous First Nation villages had been first on the scene.
He said: "Without the assistance of the First Nation community this could have been much worse."
Eyewitness Alec Dick, from nearby Ahousat, told Canada's Global News network: "They got swamped by a wave, it flipped their boat completely."
He added: "Our faster boats went out there, there were four of our local boats that transported 24 (people) to Tofino and some of them needed medical attention."
Asked if the people on board had had time to put life jackets on, he said: "I don't think they had time to do anything."
In a statement posted on the website, Mr Bray wrote: ''It has been a tragic day. Our entire team is heartbroken over this incident and our hearts go out to the families, friends and loved ones of everyone involved.
''We are doing everything we can to assist our passengers and staff through this difficult time.
''We are co-operating with investigators to determine exactly what happened.
''In the meantime, we want to extend our most sincere thank you to the first responders, rescue personnel, and everyone from Tofino and the local First Nations communities who assisted with the response efforts."