Separating the North Pacific Ocean from the Bering Sea, the Aleutian Islands are not a single sequence of islands. Actually, they're a superchain, made of up eight smaller island groups—the Andreanof, Delarof, Fox, Four Mountain, Near, Rat, Shumagin, and Sanak islands. In all, this adds up to more than 275 islands, stretching from the Alaska Peninsula in a southwesterly arc toward Japan. The islands are volcanic in origin, treeless, and alternate between towering (and frequently smoking) volcanic cones, and high tablelands. Separating the islands is some of the wildest, deepest water anywhere: on the Pacific side of the chain the water can be more than 25,000 feet deep, and the north side's Bering Canyon is twice as long as the Grand Canyon and twice as deep, bottoming out at 10,600 feet below the water's surface. The Aleutian Islands and surrounding coastal waters make up one of the most biologically rich areas in Alaska, harboring abundant seabird, marine mammal, and fish populations, the latter supporting one of the world's busiest fishing fleets.
Before the Russians arrived in the mid-1700s, the islands were dotted with Aleut villages, a total population of perhaps 3,000 people; within a hundred years that number had dropped to maybe 200 through disease and war. Today's Native communities include Nikolski, on Umnak Island; Atka, on Atka Island; and Cold Bay, at the peninsula's tip. Like everybody in the Aleutians, the descendants of the original inhabitants mostly work at commercial fishing or in canneries and as expert guides for those who hunt and fish. The settlements are quite small, accommodations are scarce, and year-round travel options are very limited.
Visitors aren't allowed on Shemya Island, which has a remote U.S. Air Force base, without special permission. Because of downsizing, the military has closed its Adak operation, and the base provides the core infrastructure for what now is a small coastal community and commercial fishing port.