largest island in the North Ayrshire council area and the historic county of Buteshire, western Scotland, on the Atlantic coast at the mouth of the Firth of Clyde. Arran is approximately 20 miles (32 km) long and has a mean breadth of 9 miles (14 km) and an area of 166 square miles (431 square km).

Arran is called “Scotland in miniature” because of the beauty and variety of its scenery. The north of the island includes the most dramatic scenery, dominated by Goat Fell, with an elevation of 2,868 feet (874 metres). The surrounding glens (valleys), notably Glen Rosa, Glen Sannox, and Glen Monamore, abound in hill and rock climbs and are well stocked with game, including grouse and red deer. In the south the landscape is gentler and more pastoral and abounds in standing stones dating from approximately 2000 BC.

Norse raiders inhabited Arran for a considerable period prior to the defeat of Haakon IV (Haakon IV Haakonsson) in 1263. The King's Caves, on the west coast, sheltered Robert the Bruce (Robert I) in the early 14th century. In 1503 Arran was awarded by royal charter to Sir James Hamilton, whose castle dominates Brodick, the island's unofficial capital. Three miles south of Brodick in Lamlash Bay lies Holy Island, a cone of basaltic rock 1,030 feet (314 metres) high containing the cave the 6th-century hermit St. Molaise used as a cell.

Because of its scenery and its accessibility to densely populated urban areas such as Glasgow, Arran has become an extremely popular holiday island and yet remains unspoiled. It is reached by steamer from Ardrossan, southwest of Glasgow. Pop. (2001) 5,058.