The Arctic National Wildlife Refuge, adjacent to the Canadian border in northeast Alaska, is one of the world's largest nature preserves. Nowhere else in North America is the transition of biotic communities from the Arctic slopes to the adjacent mountains so abrupt. Flowing northward out of the valleys of the eastern Brooks Range across the Tundra to the Arctic Ocean are three rivers, the Canning, Hulahula, and the Kongakut. They provide rare opportunities to see undisturbed plant and animal communities.
      During late-summer trips any of the Arctic National Wildlife Refuge river, it is not uncommon to see thousands of wildlife including migrating caribou, moose, musk ox, Dall sheep, wolves, grizzly bears, and waterfowl. Polar bears may also be seen near the Arctic Ocean.