Gravina Island is an island in the Gravina Islands of the Alexander Archipelago in southeastern Alaska. It is 21 miles (34 km) long and about 9.5 miles (15.3 km) wide, with a land area of 94.81 square miles (245.6 km2). The island had a population of 50 people at the 2000 census.

The Alexander Archipelago is a 300-mile (480 km) long archipelago in North America lying off the southeastern coast of Alaska. It contains about 1,100 islands, the tops of submerged coastal mountains that rise steeply from the Pacific Ocean. Deep channels and fjords separate the islands and cut them off from the mainland. The islands shelter the northern part of the Inside Passage as it winds its way among them.