Ireland, island in the North Atlantic Ocean, separated from Great Britain by St George's Channel on the south-east, the Irish Sea on the east, and the North Channel on the north-east. Politically, the island is separated into Northern Ireland, a constituent part of the United Kingdom, and the Republic of Ireland. The island is separated into four historical provinces-Connaught (Connacht), Leinster, Munster, and Ulster-and 32 administrative units called counties. The Republic of Ireland consists of Connaught, Leinster, and Munster provinces, totalling 23 counties, and 3 counties in the province of Ulster. Northern Ireland consists of 6 counties separated into 26 districts, the remainder of Ulster. The area of the island is 83,765 sq km.