Water Island () was acquired by the USA in 1917 from Denmark but continued to be owned by a corporation until several decades later. Since 1996, it has formed part of the U.S. Virgin Islands, a United States territory located in the Caribbean Sea. The island is of volcanic origin and lies to the south of Saint Thomas in the Charlotte Amalie harbor. Ferry service runs regularly from Crown Bay, Saint Thomas to Phillips Landing, Water Island; the ferry ride is about 10 minutes. At in size, Water Island is the smallest of the main U.S. Virgin Islands. It is administratively a part (subdistrict) of the St. Thomas District. Water Island is a residential island, with a population of 182 (2010 census) and no significant commercial establishments. A number of homes on Water Island are available to accommodate visitors. The main attractions are beaches, including Honeymoon Beach, plantation ruins, Fort Segarra, an underground fort partially constructed by the U.S. during World War II, and scuba diving site Supermarket Reef, in Limestone Bay. The eastmost third of the island is a gated community, Sprat Bay Estates. This includes Sprat Point, a 30 acre peninsula and nature preserve owned by the United States Department of the Interior, and private Sprat Bay Beach, located between Sprat Point and Carol Point. All beaches in the USVI are public when approached from the water.