It is 43 miles (69 km) long from east to west and 23 miles (37 km) wide from north to south and has a land area of 1,812.58 km2 (699.84 sq mi), making it the 18th largest island in the United States.

The dense spruce forests of Afognak are home to Kodiak bears, Roosevelt elk, and Sitka black-tailed deer.

The United States Census of 1890 noted a series of settlements along the beachline near the Alutiiq village of Ag’waneq (also called Afognak), including Rutkovsky village, inhabited by a group of retired employees of the Russian-American Company.

Ag’waneq was abandoned after the 1964 Good Friday earthquake devastated the island.

In the early 21st century, there are a few small logging camps and fishing lodges on the island.