Great Sitkin Island is a volcanic

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 in the Andreanof Islands

Andreanof Islands

The Andreanof Islands are a group of islands in the Aleutian Islands in southwest Alaska. They are located between Amchitka Pass and the Rat Islands group to the west, and Amukta Pass and the Islands of Four Mountains group to the east, at about 52° North and 172°57' to 179°09' West. The islands...

 of the Aleutian Islands of Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

. The island covers a total area of 60 square miles (155.4 km²) and lies slightly north of a group islands which are located between Adak Island

Adak Island

Adak Island is an island near the western extent of the Andreanof Islands group of the Aleutian Islands in Alaska. Alaska's southernmost town, Adak, is located on the island...

 and Atka Island

Atka Island

Atka Island is the largest island in the Andreanof Islands of the Aleutian Islands of Alaska. The island is east of Adak Island. It is long and wide with a land area of , making it the 22nd largest island in the United States. The northeast of Atka Island contains the Korovin volcano which...

.

The northern portion of the island is dominated by the complicated Great Sitkin Volcano which rises to a height of 5710 feet (1,740.4 m).