Ermua is a town and municipality located in the province of Biscay, in the autonomous community of Basque Country, northern Spain. In 2019, Ermua had 15,880 inhabitants.

The Deba River is a river in the Basque Country, Spain. It rises in Arlaban, into Araba province lands, and flows into the Atlantic Ocean, in the Bay of Biscay, in Deba, Gipuzkoa.