Skomer (Welsh: Ynys Sgomer) is an island off the coast of Pembrokeshire in southwestern Wales. It is well known for its wildlife: around half the world's population of Manx shearwaters nest on the island, the Atlantic puffin colony is the largest in southern Britain, and the Skomer vole (a subspecies of the bank vole) is unique to the island. It is also known for its archeological interest: stone circles, standing stone and remains of prehistoric houses. Skomer is a national nature reserve, a Site of Special Scientific Interest and a Special Protection Area. Much of the island has also been designated an ancient monument. It is surrounded by a marine nature reserve and is managed by the Wildlife Trust of South and West Wales.