Thus , Innis traveled extensively beginning in the summer of 1924 when he and a friend paddled an 18 @-@ foot ( 5 @.@ 5 m ) canvas @-@ covered canoe hundreds of miles down the Peace River to Lake Athabasca ; then down the Slave River to Great Slave Lake . They completed their journey down the Mackenzie , Canada 's longest river , to the Arctic Ocean on a small Hudson 's Bay Company tug . During his travels , Innis supplemented his fur research by gathering information on other staple products such as lumber , pulp and paper , minerals , grain and fish . He traveled so extensively that by the early 1940s , he had visited every part of Canada except for the Western Arctic and the east side of Hudson Bay .