Mackenzie River east into the Churchill River. The eastern portion of the Mackenzie basin is dominated by vast reaches of lake-studded boreal forest and includes many of the largest lakes in North America. By both volume and surface area, Great Bear Lake is the biggest in the watershed and third largest on the continent, with a surface area of and a volume of . Great Slave Lake is slightly smaller, with an area of and containing of water, although it is significantly deeper than Great Bear. The third major lake, Athabasca, is less than a third that size with an area of
Boats of the Mackenzie River watershed Landing north of Edmonton to the Slave River rapids, the only significant obstacle en route to the Mackenzie. In 1886, the S.S. "Wrigley" was launched on the other side of these rapids, at Fort Smith, and for the first time a steam-driven vessel operated on the Mackenzie River as far as Aklavik in the river delta before it spilled into the Arctic Ocean. A series of small portage trails were established between Smith's Landing (later Fort Fitzgerald) and Fort Smith to skirt the 16-mile rapids - this was later upgraded into a full road in the 1920s. In 1898 the