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
Mackenzie River Providence, which was historically an important ferry crossing in the summer, and used as an ice bridge in the winter for traffic along the Yellowknife Highway. In 2012 the Deh Cho Bridge was completed at a point about upstream, providing a safer permanent crossing. It is the only bridge across the main stem of the Mackenzie. West of Fort Providence the Mackenzie widens considerably, resembling a shallow, swampy lake more than a river; one large widening here is known as Mills Lake. After heading west for about the Mackenzie narrows and turns northwest through a long stretch of fast water