BISCAY, Bay of, an extensive gulf or bay of the Atlantic, between the northern coast of Spain and the western coast of France. It extends from the island of Ushant, off Brest, to Cape Ortel on the north coast of Galicia. The Spanish coast is almost wholly bold and rocky; the French is more varied, and from the mouth of the Gironde southward to the Adour is low and sandy. The openness of this bay, the strong westerly winds, and the current (Rennel's) which sets in from the west and sweeps along its southern and eastern shores, impede its navigation. It receives the waters of the Loire, Charente, Gironde, and Adour.