Orkney, also known as the Orkney Islands, is an archipelago off the north coast of mainland Scotland. The plural name the Orkneys is also sometimes used, but is now considered incorrect. Part of the Northern Isles along with Shetland, Orkney is 10 miles north of Caithness and has about 70 islands, of which 20 are inhabited. The largest island, the Mainland, has an area of 523 square kilometres, making it the sixth-largest Scottish island and the tenth-largest island in the British Isles.