Born in Fredrikstad, Norway, Larsen took out Canadian citizenship in 1927 and in 1928 he enlisted in the Royal Canadian Mounted Police. Shortly thereafter he was assigned as master of the St. Roch. Rising to the rank of Sergeant, in 1940 Larsen was ordered to attempt to navigate the Northwest Passage. The St. Roch became the second ship to sail the passage, the first to sail it from West to East, and the first ship to sail it both ways in a single season. The St. Roch left Vancouver on June 23, 1940 reaching Halifax harbour on October 11, 1942. In 1944, the St. Roch left Halifax, arriving in Vancouver on October 16, 1944. The St. Roch later went on to become the first vessel to circumnavigate the North American continent.
A life size bronze sculpture of Captain Larsen was commissioned by the Vancouver Maritime Museum and installed on the port foredeck of the RCMP Vessel St. Roch in July of 2006.