The Twin Lights stand at the north and southeast sides of Thacher Island. The island, located about one mile off the coast of Rockport, Massachusetts, is comprised of about 50+/- acres of rock, covered by a minimal amount of land cover. The island is located about 30 miles north of Boston, and about two miles from Gloucester Harbor. A small number of late 19th century wooden houses and structures are clustered near the southeast light tower. The south tower and southeastern portion of the island, about 28 +/- acres, is maintained by the Coast Guard as of 2000. The north tower and northern end of the island, approximately 22 acres, is owned by the U.S. Fish and Wildlife Service and is leased from them by the town of Rockport. The south end of the island is to be transferred to the Town of Rockport. The property consists of the following: