At 3,588 square miles, Kodiak Island is the largest island in the group and the second largest island in the United States. Only the island of Hawaii is larger. The City of Kodiak, at the northeastern tip of the island, is about 250 miles south of Anchorage. The city serves as the major supply and transportation hub for the archipelago's six villages.

Although the main population center surrounds the City of Kodiak, there are also six small cities in the Kodiak Archipelago. Five are located on Kodiak Island and one is on Spruce Island. Each of the cities can be reached by aircraft or boat.

The archipelago is a continuation of the Kenai Mountain Range, which begins on the Kenai Peninsula, 90 miles to the north. Lying in the Aleutian Trench, the archipelago has been strongly influenced by both volcanic and seismic activity along the "chain of fire."