Afognak is an island in the Kodiak Archipelago 5 km north of Kodiak Island in the U.S. state of Alaska. It is 43 miles long from east to west and 23 miles wide from north to south and has a land area of 1,812.58 km², making it the 18th largest island in the United States. The coast is split by many long, narrow bays. The highest point is 2,546 feet.