arm of the Bering Sea (Bering Sea and Strait), indenting for 200 mi (320 km) the southwest coast of Alaska, U.S.; its mouth extends for 270 mi between Cape Newenham (north) and the southwest end of the Alaska Peninsula (south). Its shoreline includes the individually named bays at the mouths of the Togiak, Nushagak, Kvichak, and Ugashik rivers. The shallowness of Bristol Bay limits navigation to small salmon-fishing vessels.