The Republic of Ireland lies in the north Atlantic Ocean and is separated from Britain by the Irish Sea to the east. The northeastern part (Northern Ireland) is part of the United Kingdom. The country has a central plain surrounded by a rim of hills and mountains offering some of the most varied and unspoilt scenery in Europe. Quiet sandy beaches, semi-tropical bays warmed by the Gulf Stream, and rugged cliffs make up the 5600km or 3500 miles of coastline.