Ireland, island off the northwestern coast of mainland Europe that is the westernmost major island of the British Isles. It is divided politically into Ireland (which occupies the southern five-sixths of the island) and Northern Ireland (a constituent part of the United Kingdom). It is bounded on the north, west, and south by the Atlantic Ocean and is separated from Great Britain on the northeast by the North Channel, on the east by the Irish Sea, and on the southeast by Saint George’s Channel.
The island’s greatest length north-northeast to south-southwest, from Benmore Head (Causeway Coast and Glens, Northern Ireland) to Brow Head (Cork), is 306 miles (492 km), and its greatest breadth east to west is 182 miles (293 km). Brow Head is the most southerly point on the mainland, although there are islands farther south, and Malin Head (Donegal) is the most northerly point. The most easterly point is on the coast of the Ards Peninsula (Ards and North Down, Northern Ireland), and the most westerly is Dunmore Head on the Dingle Peninsula (Kerry). Ireland averages 110 miles (177 km) in breadth and 220 miles (354 km) in length; its area is 32,595 square miles (84,421 square km).
The minimum distance from Great Britain is 13 miles (21 km), between the Mull of Kintyre (Scotland) and Torr Head (Northern Ireland). The narrowest crossings of St. George’s Channel are about 50 miles (80 km) in the south and 70 miles (113 km) in the north. The distance from Holyhead, Wales, to Dublin across the Irish Sea is 65 miles (105 km).
Ireland, as part of the Atlantic fringe of Europe, has been called “the last outpost of Eurasia.” Many of its physical features bear an obvious resemblance to those of Great Britain, yet it is best regarded as a separate land, possessing a landscape molded by a different physical and human history. Ireland’s highest point is Carrantuohill (3,414 feet [1,041 meters), a mountain in Macgillycuddy’s Reeks, a range on the Iveragh Peninsula, County Kerry. The island’s longest river is the Shannon, which rises in northwestern County Cavan and flows for about 161 miles (259 km) in a southerly direction to enter the Atlantic Ocean via a 70-mile (113-km) estuary below Limerick city.
See individual articles on Ireland and Northern Ireland.