Flowing into the Beaufort Sea, for 10 points, identify this river that begins at Great Slave Lake, the longest in Canada.
Russian satellite Cosmos 954 plunged into this river's source in 1978. The Liard River joins it at Fort Simpson, and the Redstone and Keele rivers enter it north of Wrigley. This river broadens to four miles in width at Norman Wells, and its water transportation routes terminate at Tuktoyaktuk, North of the Sans Sault Rapids. Its namesake, discovering that it did not terminate in Cook Inlet, dubbed it "Disappointment River" after exploring from a trading post of Fort Chipewyan on Lake Athabasca. Flowing into the Beaufort Sea, for 10 points, identify this river that begins at Great Slave Lake, the longest in Canada.
Russian satellite Cosmos 954 plunged into this river's source in 1978.
Mackenzie River