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
Geikie River (Saskatchewan) Fond du Lac River which flows out of the lake to the north-west where it drains into Lake Athabasca which ultimately drains into the Arctic Ocean via the Mackenzie River system, or into the Cochrane River which flows out of the north-eastern side of the lake and into Reindeer Lake which drains via the Churchill River system into Hudson Bay. If Hudson Bay is defined as part of the Atlantic Ocean then the Geikie River is the largest river in the world that drains naturally into two oceans. The Geikie River is bridged by Highway 905 at the highway's 184