Wales is a country that is part of the United Kingdom and the island of Great Britain. It has over 1,200 km (746 mi) of coastline, including its offshore islands; the largest, Anglesey (Ynys Môn). Generally mountainous, its highest mountains are in the north and central areas, especially in Snowdonia (Eryri), which contains Snowdon (Yr Wyddfa), its highest peak.