Boal is a municipality, a civil parish and a town in the Principality of Asturias, an autonomous community in northern Spain. The municipality is located in the western part of Asturias, near the region's coastline with the Bay of Biscay.
Boal is bordered by several other Asturian municipalities: El Franco and Coaña to the north, Illano to the south, Castropol to the west, and Villayón to the east. This places it within the comarca of Eo-Navia, a district in western Asturias.
The municipality contains both the town of Boal itself and the surrounding rural parishes that make up the wider administrative area. As with other municipalities in the region, it forms part of the traditional and administrative structure of Asturian local government.