The Athabasca is the longest and largest river in Alberta, and one of the few in Western North America unaltered by human impoundment. The River begins and ends at two of the most spectacular and significant natural features in the world. It rises in the Columbia Icefield, the hydrological apex of North America, and finally empties into Lake Athabasca and the 4100 square kilometre Peace-Athabasca Delta, one of the largest inland freshwater deltas in the world. The river was once a major shipping artery for goods into Canada's north and west, and the small town of Athabasca Landing commemorates that energetic time. The river travels through the massive oil sands north of Fort McMurray, and passes an area of migrating sand dunes that may be the largest and most northerly dune complexes in North America.