The island of Ireland is located in the north-west of Europe, between latitudes 51° and 56° N, and longitudes 11° and 5° W. It is separated from the neighbouring island of Great Britain by the Irish Sea and the North Channel, which has a width of 23 kilometres (14 mi) at its narrowest point. To the west is the northern Atlantic Ocean and to the south is the Celtic Sea, which lies between Ireland and Brittany, in France. Ireland has a total area of 84,421 km2 (32,595 sq mi) Ireland and Great Britain, together with many nearby smaller islands, are known collectively as the British Isles. As the term British Isles is controversial in relation to Ireland, the alternate term Britain and Ireland is often used as a neutral term for the islands.
A ring of coastal mountains surround low plains at the centre of the island. The highest of these is Carrauntoohil (Irish: Corrán Tuathail) in County Kerry, which rises to 1,038 m (3,406 ft) above sea level. The most arable land lies in the province of Leinster. Western areas can be mountainous and rocky with green panoramic vistas. The River Shannon, the island’s longest river at 386 km (240 mi) long, rises in County Cavan in the north west and flows 113 kilometres (70 mi) to Limerick city in the mid west.
The island’s lush vegetation, a product of its mild climate and frequent rainfall, earns it the sobriquet the Emerald Isle. Overall, Ireland has a mild but changeable oceanic climate with few extremes. The climate is typically insular and is temperate avoiding the extremes in temperature of many other areas in the world at similar latitudes. This is a result of the moderating moist winds which ordinarily prevail from the South-Western Atlantic.
Precipitation falls throughout the year but is light overall, particularly in the east. The west tends to be wetter on average and prone to Atlantic storms, especially in the late autumn and winter months. These occasionally bring destructive winds and higher total rainfall to these areas, as well as sometimes snow and hail. The regions of north County Galway and east County Mayo have the highest incidents of recorded lightning annually for the island, with lightning occurring approximately five to ten days per year in these areas. Munster, in the south, records the least snow whereas Ulster, in the north, records the most.