The principal and largest island of the Shetland Islands group, and the third-largest island in Scotland, Mainland is narrow and long, extending for 50 miles (90 km) from north to south. Its coastline is much indented by voes and inlets. The North Mainland has a particularly complex coastline and narrows to just 100m (328 feet) in width at Mavis Grind. The South Mainland is rarely wider than 3 miles (5 km), while the West Mainland forms a large lobe mostly comprising the Walls Peninsula. The principal town of the island, Lerwick, lies on an inlet on the east coast of the Central Mainland, with the second settlement, Scalloway, on the opposite coast just 5 miles (8 km) distant. The population of the Shetland Mainland was 13282 (1961), 12944 (1971), 17722 (1981), 17562 (1991) and 17550 (2001), growing to 18765 (2011). Hjaltland is the Old Norse name for the island, and derives from the 'hilt' of a sword.