Mackenzie River great depths to bedrock. A characteristic feature of the delta is its numerous pingos, or hills of earth-covered-ice – some 1,400 of them. The Peel River, carrying much of the runoff from the northern Yukon, joins in the delta at a point northeast of Fort McPherson. Below there, the Mackenzie diverges into several large channels with the largest heading north-northeast, emptying into the Beaufort Sea west of Tuktoyaktuk. At , the Mackenzie River drainage basin encompasses nearly 20 percent of Canada. About , or 54 percent of the basin, lies above Great Slave Lake. Permafrost underlies about three-quarters of the
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