a sea port town of Spain, in Biscay, and in the territory of Guipuscoa, seated on a peninsula on the sea shore, and on the river Bidafoa. It is small, but well fortified both by nature and art; and has a good harbour, though dry at low water. It is built in the form of an amphitheatre, on the declivity of a hill, and surrounded on the land side by the lofty Pyrenean mountains. It is a very important place, being accounted the key of Spain on that side. W. Long. i. 43. N. Lat. 43. 23.