The Athabasca River
Athabasca River, a river in Canada. The Athabasca, a tributary of the Mackenzie, has its source in the glaciers of the Canadian Rockies in Jasper National Park. It winds generally northeastward for about 765 miles (1,231 km) across Alberta and empties into Lake Athabasca. Chief tributaries include the Pembina and Clearwater rivers. Oil sands along the lower Athabasca contain some of the world's largest known petroleum reserves.