It starts at the confluence of the Dezadeash and Kaskawulsh rivers in Kluane National Park and Reserve. After flowing south into the northwestern tip of British Columbia, it is joined by the Tatshenshini River in Tatshenshini-Alsek Park. It reaches the Pacific Ocean at Dry Bay, in the Gulf of Alaska, south of Yakutat, Alaska close to the northern end of the Alaska Panhandle. Although the river is navigable by kayak or rubber raft in its northern reaches, it rapidly becomes unnavigable—for any but the most experienced and skilled kayakers—at Turnback Canyon.
On older maps, the Alsek river is labeled as the Tatshenshini and vice versa. Some Yukon First Nation elders also refer to the river as the Tatshenshini.
The river flows next to the Lowell glacier which blocked off the river from 1725 to 1850 and created a large lake behind it. When the glacier broke in 1850, it created a massive flood, washing away everything in its path on the way to the Pacific.
The river carries a lot of silt from the Alsek lake/glacier, which contributes to the rivers low temperature.
The Alsek and nearby East Alsek rivers were at one time connected, and the old river bed can still be made out on some maps.
The Alsek glacier contacts the Grand Plateau glacier, which faces the shoreline. Also in the same general area are the Doame foothills and Doame river.
In 1958, a magnitude 7.7 earthquake centered near Lituya bay significantly changed the lay of the land. The earthquake caused the Doame river and East Alsek river to join together.
The area also supports subsistence and sport fishing. There are multiple local sport fishing, sight-seeing, hunting, and animal watching lodges
Researchers from University of Colorado provide details of new studies and findings in the area of paleolimnology.
Nov 09, 2010; "We have gained new insight into the dynamic late Holocene paleohydrology and paleolimnology of Kluane Lake by reconstructing...