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
Mackenzie River which empty into the Pacific Ocean. Lowland divides in the north separate the Mackenzie basin from the Arctic Ocean watersheds of the Anderson, Horton, Coppermine and Back Rivers. In the east, the Mackenzie borders on the Hudson Bay watersheds of the Thelon and Churchill Rivers, and to the south it is bordered by the Saskatchewan–Nelson River system, which also empties into Hudson Bay. The Mackenzie system is hydrologically connected to the Hudson Bay watershed via Wollaston Lake, which is not only the source of the Fond du Lac tributary of Lake Athabasca, but also of the Cochrane River, which flows