Mauritius is a volcanic island, measuring 58km (36mi) from north to south and 47km (29mi) from east to west - about two-thirds the size of Luxembourg or the US state of Rhode Island. It lies in the Indian Ocean, roughly 800km (500mi) east of Madagascar, 3860km (2400mi) south-west of India and 220km (135mi) north-east of its nearest neighbour, Réunion. With about 600 people per square kilometre, Mauritius has one of the highest population densities in the world. As a country, it includes the inhabited island of Rodrigues, some 560km (350mi) to the north-east, and other scattered coral atolls such as Cargados Carajos and Agalega.