Great Sitkin Island (Aleut: Sitх̑naх̑;[1] Russian: Большой Ситкин) is a volcanic island in the Andreanof Islands of the Aleutian Islands of Alaska. The island covers a total area of 60 square miles (160 km2) and lies slightly north of a group of islands which are located between Adak Island and Atka Island.
The northern portion of the island is dominated by the complex Great Sitkin Volcano which rises to a height of 5,710 feet (1,740 m). The island is 18 kilometres (11 mi) long and 16.94 kilometres (10.53 mi) wide.