The island of Ireland is the 3rd largest island in Europe. It has 3700km of coastline and is bordered by the Atlantic Ocean to the west and the Irish Sea to the east. The north and south coasts are bordered by the North Channel and the Celtic Sea respectively. 

The most northerly point on the island is Mallin Head, Co. Donegal, and Mizen Head, Co. Cork is the most southerly. Ireland's highest mountain is Carrantuohill, which is the central peak of the Macgillycuddy's Reeks range in Co. Kerry. It rises 3414 ft/1050m above sea level.

The River Shannon is 386km long and the country's longest river. Its source is in Cuilcagh Mountains Co.Cavan and it enters the Atlantic Ocean in Co. Limerick, having flowed through four counties.

Lough Neagh, Northern Ireland, which is 396 km² is the island's largest lake. It forms part of counties Tyrone, Londonderry, Antrim, Down and Armagh.