Muscle Ridge Islands is an archipelago and unorganized territory off the coast of South Thomaston in Knox County, Maine, United States. The population was 9 at the 2020 census.

Geography

According to the United States Census Bureau, the unorganized territory has a total area of 49.7 square miles (128.6 km), of which 0.95 square miles (2.45 km) is land and 48.7 square miles (126.2 km) is water (98%). The archipelago includes over a dozen islands, including Andrews, Dix, Fisherman, Pleasant, Graffam, and Two Bush Island, which is home to the Two Bush Island Light.