Biscay is a province of the Basque Autonomous Community, heir of the ancient Lordship of Biscay, lying on the south shore of the eponymous bay. The capital and largest city is Bilbao.

Busturialdea, also named Busturialde - Urdaibai is a comarca of the province of Biscay, in the Basque Country, Spain. It is the heir of "Busturia", one of the original merindades that used to compose