TWO Swindon men have died after a whale watching boat sank off Tofino in Canada on Sunday afternoon.

Family have confirmed West Swindon’s David Thomas, 50, and his son Stephen, 18, are among the five British nationals who died when the 65ft-long Leviathan II went down off the coast of Vancouver Island.

The University of Nottingham student Paul Thomas, 22, said his mother Julie was also on the boat, but survived and is recuperating in hospital with minor injuries.

Stephen's mother Julie was rescued from the stricken vessel, Leviathan II, along with 20 other people on board.

Mr Thomas will fly to be with his mother this afternoon and has asked the public respect his family’s privacy.

Britons Jack Slater, 76, and 29-year-old Katie Taylor were also killed, sources said.

Investigators from the Transportation Safety Board of Canada (TSB) have begun their inquiry into what happened to the vessel, which was carrying 24 passengers and three crew.

A 27-year-old man from Sydney is missing, Australia's Department of Foreign Affairs and Trade said.

The missing man's girlfriend's father was among the dead, the Australian Associated Press reported.

The victims included an 18-year-old man and another man aged 76, Barbara McLintock, from the British Columbia coroner's office said.

She confirmed 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 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.

The company's owner Jamie Bray said people were "traumatised" and in "disbelief" at what had happened.

Microsoft paid tribute to Mr Thomas - who worked for the company - and his son.

Michel Van der Bel, area vice president and general manager at Microsoft UK, said: "We are shocked and saddened by the death of David Thomas, a Microsoft employee, and his son in the tragic boating accident in Canada.

"Our thoughts and deepest sympathies are with their family, friends and David's colleagues and we will be doing everything we can to support them."

The Down's Syndrome Association described Stephen as a "very talented young man" and a "gifted photographer", while his father was a "huge supporter" of the charity.

The charity's chief executive, Carol Boys, said: "Everyone at the Down's Syndrome Association and the Swindon Down's Syndrome Group were deeply saddened to hear the news of the deaths of Stephen and David Thomas.

"Stephen was a very talented young man and a gifted photographer. His love of photography started when he was eight years old. We were all delighted when Stephen's beautiful image Moraine Lake won the national My Perspective photographic competition last year.

"Stephen's father David was a huge supporter of the Down's Syndrome Association and one of the driving forces behind the Swindon Down's Syndrome Group, where he was a trustee.

"All of our thoughts and condolences are with the Thomas family at this terrible time."

Stephen, who was a keen photographer, posted some of his work on his blog called Stephen's View, writing: "I am really interested in photography. I like taking pictures of flowers, landscapes and people."

His father, who had his own amateur photography website, described himself as a "committed Christian" who was "in constant awe at the wonders of God's creation".

In a Facebook post, Gateway Church Swindon said Mr Thomas and his son were active members of the church community, adding: "These two men brought smiles and encouragement to all who knew them and they will be greatly missed."

Swindon College, where Stephen had enrolled on a course last year, described him as a "firm favourite of students and staff".

Andrew Parsons, the college's curriculum area manager for foundation learning, said: "During a Bugsy Malone performance, last June, Stephen demonstrated his infectious lust for life and was one of the star performers during the two nights of shows.

"Stephen was an enthusiastic learner who was always willing to try new things and had a keen interest in many subjects, particularly art.

"All of our thoughts, condolences and sympathies are with the family at this difficult time. Stephen will be sorely missed by all of the staff and students of the foundation learning department."

A Gofundme page has been set up for Mrs Thomas and Swindon Down's Syndrome Group here:

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Five Britons died when Leviathan II, above, sank off Vancouver Island on a whale watching trip

Fisherman Clarence Smith said he was reeling his lines for halibut when his friend saw a flare shoot in the sky and they raced to the scene in their small boat, seeing people in life rafts, in the water, and on rocks.

They first helped a man who was clinging to the side of the boat, taking eight minutes to get him on board. He was unresponsive, and tangled in a line.

Then they rescued two women who were clinging to each other, and finally got 10 people on the life raft onto their boat.

Among those they picked up were 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."

The boat capsized about eight nautical miles (14.7 kilometres) off Tofino, a popular destination for whale watchers.

A spokeswoman for the Vancouver Island Health Authority said late on Monday that four of the survivors remained in hospitals in British Columbia and were all in a stable condition.

The boat began to take on water around two hours and fifteen minutes after it took off on its whale watching tour, the Transportation Safety Board of Canada said. Investigators will now examine the wreckage of the vessel, its maintenance history and and consider the weather conditions at the time.

Marc Andre Poisson, director of marine investigations for Canada's Transportation Safety Board, said the crew and passengers had not yet been spoken to.

He said it was too early to say what caused the boat to capsize or what the contributing factors might be. The vessel has been towed to a nearby island but remains mostly submerged.

"We're still at the early stages right now," he said, adding that the investigation could take months.

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Transportation Safety Board member Marc Andre Poisson, above, speaks during a news conference. Picture: Chad Hipolito/The Canadian Press via AP 

The Royal Canadian Mounted Police sent an underwater recovery team to search for the missing Australian man, with assistance from the coast guard and local search and rescue personnel.

Following the incident company owner Mr Bray said passengers on the boat were not required to wear life jackets.

"On larger vessels we're not required to have the passengers wear the life jackets. On smaller open boats they are," he said.

The company suffered a previous fatal accident, with a boat becoming swamped and rolling to an angle in 1998, killing the captain and a tourist, and an incident two years earlier when a captain suffered head injuries, but survived, after falling asleep and running a boat aground.

Foreign Secretary Philip Hammond said his thoughts were with the family and friends of those affected by Sunday's incident, while Canadian prime minister-designate Justin Trudeau said he was "shocked and saddened" by the deaths.

Locals held a dinner on Monday evening at the Tofino community hall to remember those affected by the tragedy.

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A woman lights a candle at a memorial to remember those involved with the Leviathan II whale watching boat. Picture: Chad Hipolito/The Canadian Press via AP