The Alaska Peninsula is a peninsula extending about 800 km (497 mi) to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The peninsula separates the Pacific Ocean from Bristol Bay, an arm of the Bering Sea. In literature (especially Russian) the term ‘Alaska Peninsula’ was used to denote the entire northwestern protrusion of the North American continent, or all of what is now the state of Alaska, exclusive of its panhandle and islands. The Lake and Peninsula borough, the Alaskan equivalent of a county, is named after the peninsula.