How did a WWII merchant shipping vessel sink off the B.C. coast?

There is an underwater search for answers off the coast of British Columbia that could “officially” solve a mystery dating back to the Second World War.

The American merchant vessel S.S. Coast Trader sank on June 7, 1942 off the coast of Cape Flattery near Washington State, just 56 kilometres from Vancouver Island. There was one fatality among the crew of 56, a cook who died in a lifeboat from exposure.

While it had all the markings of an attack by a Japanese submarine, American officials said it was sunk by an internal explosion.

WATCH: There is an underwater search for answers off the coast of British Columbia that could solve a mystery dating back to the Second World War. Kylie Stanton explains.

2:03 How did WWII merchant shipping vessel sink off B.C. coast?

“The military officials discounted the fact that it was a submarine torpedo hit. They said the boiler exploded and that’s what led to the sinking of the vessel. This, despite the fact numerous crew were saying we saw a submarine – we saw the coning tower that actually surfaced,” said Ken Burton, Executive Director of the Vancouver Maritime Museum.

Following the attack on Pearl Harbour, the government regularly suppressed news of Japanese attacks close to the American coastline, trying to avoid increasing fear among the general public. And while it had long been believed that the Japanese submarine I-26 was responsible, there had never been confirmation.

But this week, the E/V Nautilus has come to explore the wreck, using remotely operated vehicles to get a closer look.

The point of impact from a single torpedo is clear, giving visual proof of what historians have said for decades.

“It certainly changes the script of World War Two for the west coast of Canada,” said Burton.

“The significance is, is that it actually brings the battle in the Pacific in the Second World War right to our shores.”