A freighter sunk by a Japanese submarine in World War II has been seen by human eyes for the first time in almost 75 years.

On Jun. 7, 1942, the SS Coast Trader was off the coast of Vancouver Island near Victoria when it was struck by a Japanese torpedo. It sank in less than an hour and remained undisturbed until this week.

A remotely operated underwater vehicle (ROV) explored the vessel, June 2, through a partnership involving the exploration vessel Nautilus, the Ocean Exploration Trust, and the National Oceanic and Atmospheric Administration (NOAA).

Jim Delgado, the NOAA;s director of maritime heritage coordinated the ROV mission from Rhode Island and told All Points West host Robyn Burns they were out to answer a few key questions, including how intact the vessel was, as it was carrying about 7,000 of drums of oil.

The SS Coast Trader makes a port call to San Fransisco in 1937. (NOAA)

"She's sitting in a very ecologically sensitive area. If she were to release that oil, it would impact the west coast of Vancouver Island," he said.

"The original assessment, that the risk of a leak would be low to medium — I think we're going to downgrade that to low, because this ship, other than the area of the stern and the area the of torpedo, is very intact."

Researchers also wanted to know exactly how it went down. Although it was believed sunk by a Japanese submarine a week shy of 74 years ago, there were theories that a boiler explosion was actually responsible.

"You can see right down into the boiler flats, and they're intact," Delgado said. "I've seen other torpedoed ships and this is definitely major damage and consistent with the damage of a Type 93 Japanese torpedo."

Delgado says because the vessel looks stable and at low risk of a leak, there probably will be no work done to recover the oil. He says it would be very expensive, and since it's so deep down, the oil has probably formed a "tar" with the water and wouldn't travel far.

"This thing looks as solidly riveted as when it was built — except for where the torpedo hit it."

With files from CBC Radio One's All Points West

Fish have now made their homes amid the wreckage of the SS Coast Trader, laying at the bottom of the Pacific Ocean. (NOAA)

To hear the full story, click the audio labelled: Sunk off Vancouver Island in 1942 by Japanese sub, SS Coast Trader explored for first time