Perkins Township (Swan Island) is an unorganized territory in Sagadahoc County, Maine, United States.

The Swan Island Historic District comprises most of the township, with eight buildings, five structures and 1,500 acres (610 ha).

[citation needed] According to the United States Census Bureau, Swan Island has a total area of 9.7 km2 (3.7 mi2), of which 5.8 km2 (2.2 mi2) is land and 3.9 km2 (1.5 mi2) (40.37%) is water.

Swan Island is 4 miles (6.4 km) long and relatively narrow, with its northernmost tip roughly opposite the village center of Richmond, across the main channel of the Kennebec River, and whose southernmost tip is just north of the northern extent of Merrymeeting Bay.

The land is a mix of woods and former fields, a proportion that is maintained by the state as part of its wildlife management activities.