It is a coastal plain extending to the Bering Sea, covering the delta created by the Yukon and Kuskokwim rivers.

[4] The refuge's coastal region bordering the Bering Sea is a rich, productive wildlife habitat supporting one of the largest concentrations of water fowl in the world.

There are also very large seasonal concentrations of northern pintail, loon, grebe, tundra swan and cranes.

Often trailed by the wolves, some of the 150,000+ Mulchatna caribou herd migrate onto the eastern tundra areas during the fall and winter.

Walrus, seals, sea otter and porpoise can be found in the waters as well as Orca, beluga, gray, humpback, bowhead and minke whale.