Inch Island is an island in Lough Swilly, Co Donegal. The island is around five square miles (13 square kilometres) in area. It lies off the Donegal coast near Burt and the start of the Inishowen Peninsula. It is connected to the mainland by a causeway road. The island's highest hill is at 222m. The island features a 15th century castle on a cliff overlooking Lough Swilly, as well as two churches, one Presbyterian and the other Catholic. Inch island is a well known birdwatching site with a relevant population of migratory and wintering birds. Bird species on the island include Greenland white fronted goose, whooper swan and greylag goose.