The Bay of Biscay, known in Spain as the Gulf of Biscay, and in France and some border regions as the Gulf of Gascony, is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Point Penmarc'h to the Spanish border, and the northern coast of Spain west to Cape Ortegal. The south area of the Bay of Biscay that washes over the northern coast of Spain is known locally as the Cantabrian Sea.
The average depth is 1,744 m (5,722 ft) and the greatest depth is 4,735 m (15,535 ft).
The Plaiaundi Ecology Park is a 24 -hectare coastal wetland lying where the Bidasoa River meets the sea in the Bay of Biscay.The nature of Plaiaundi consists of a wide variety of flora (visitors view them mainly in the spring) and fauna (visitors with binoculars arrive all during the year, because of the birds migratory habits).This nature park contains a variety of birds, reptiles, mammals and insects.