Monhegan is a plantation in Lincoln County, Maine, United States, about 12 nautical miles off the mainland. The population was 69 at the 2010 census. The plantation comprises its namesake island and the uninhabited neighboring island of Manana. The island is accessible by scheduled boat service from Boothbay Harbor, New Harbor and Port Clyde. Visitors' cars are not allowed on the island. It was designated a National Natural Landmark for its coastal and island flora in 1966.