Almost every famous explorer in history sailed out in search of the Northwest Passage at one point or another. Cortes, Cook, Columbus: the all sought out mythical sea route connection the Atlantic to the Pacific that would hold the key to trade with all of Asia. In the later centuries when no such passage was discovered running through the heart of the North American continent, explorers discovered a semi-passable route running through the arctic north. But severe weather and icy conditions precluded a complete voyage by ship for nearly a century.

On this day, June 21, in 1940 Corporal Henry Larsen of the Royal Canadian Mounted Police set out to do what only one other person in history did: to sail all the way across the Northwest Passage.

Larsen’s ship of choice was the St. Roch, built in 1928 out of American Douglas firs and Australian gumwood. She was a sturdy ship, built with an extra thick hull to protect against the ice floes, and after 12 years of service in the RCMP she served a further four in Larsen’s two epic expeditions across the half-frozen waterway.