Reserve of Urdaibai's Biosphere

URDAIBAI has a great diversity of landscapes, carved out by its rivers as they race down to the Bay of Biscay coast. Three main types can be distinguished: mountainsides – steep but not extremely high – with green, flat-bottomed valleys, then river plains and marshes closer to the coast and finally the narrow strip of cliffs, harbours and beaches that mark the shoreline.