Guarding the southern entrance to Scapa Flow in the Orkney Islands, the 'flat' island of Flotta, with an area of 876 ha (2165 acres), lies to the west of the Sound of Hoxa which separates it from South Ronaldsay. During the 20th-century it has played two important maritime roles, first as a naval base during two world wars and secondly as an oil terminal linked in 1977 by a 142-mile (230-km) pipeline to the Piper and Claymore fields in the North Sea. The island has an airfield as well as ferry links with Hoy and Mainland Orkney, and employment is associated with farming, fishing and the oil installation. The population is recorded as 123 (1961), 73 (1971), 178 (1981), 126 (1991), 81 (2001) and 80 (2011). The highest point on Flotta is West Hill at 58m (190 feet) and Pan Hope, a shallow bay to the east, was the site of salt pans during the 17th century. Prime Minister, Margaret Thatcher (1925 - 2013) visited the island and the Flotta Oil Terminal in 1980.