Five British nationals died when a whale watching boat with 27 people on board sank off Vancouver Island.
One person is still missing and the rest were rescued, some by members of the local aboriginal community who rushed to the scene.
The vessel made a mayday call late on Sunday afternoon on a calm, clear and sunny day off the tourist community of Tofino – a popular destination for whale watchers, the Joint Rescue Coordination Centre said.
The cause of the sinking remains a mystery.
British Foreign Secretary Philip Hammond confirmed in a statement that the five killed were UK nationals.
He said consular officials in British Columbia were supporting family members of those who died.
“My thoughts are with the family and friends of all those affected by this terrible accident,” Mr Hammond said.
A search by the rescue agency staffed by Canadian military and Coast Guard personnel concluded late on Sunday with 21 rescued and one person missing, said Lt.-Cmdr Desmond James, a spokesman for rescue agency.
The Royal Canadian Mounted Police will take over the search for the missing person.
Boats from the nearby Ahoushat First Nation arrived first on the scene, said aboriginal Councillor Tom Campbell.
He was on the waterfront and watched as rescuers brought several survivors ashore. He said his cousin pulled at least eight people from the water onto a boat.
The boat, the 20-metre Leviathan II, was partially submerged eight nautical miles west of Tofino.
Canadian Prime Minister-designate Justin Trudeau thanked all those who participated in the rescue effort and offered his condolences to the victims and their families.
“I know firsthand of this coastal area’s natural beauty and the many people who visit here from all around the world,” said Mr Trudeau, who won Canada’s national elections last week.
“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.”
Many of the survivors were taken to Tofino General Hospital and some were already discharged Sunday night, said Valerie Wilson, a spokeswoman for the Vancouver Island Health Authority.
Canada’s Transportation Safety Board said it was investigating the boat’s sinking.