Castropol is a municipality in Asturias, Spain. It is also the name of a parish within the municipality and a town within the parish. The municipality of Castropol has a population of 3696 (INE, 2014). It is bounded on the north by the Cantabrian Sea and on the west by a coastal inlet, or ria, which separates it from the municipality of Ribadeo in Galicia, called the river Eo. To the west it is bordered by Tapia de Casariego, by El Franco, Boal and other Asturian municipalities, and to the south by Vegadeo and Villanueva de Oscos.