The coastline of northern Atlantic Iberia, by comparison with Ireland, Norway or Scotland is relatively unindented. That fact should not delude anybody into believing that physical geography has been unkind, as there are a number of excellent inlets, drowned bays and extensive rias, which have offered splendid conditions for the evolution of ports. In was in these kinds of situations that the ports of Bilbao, Xixón, Santander and Pasajes evolved. A chain of parallel sierras running at right angles to the coast has been one of the main obstacles arresting the expansion of port hinterlands in northern Atlantic Spain. It is a theme we will have cause to return to later in this chapter (Madrazo, 1984). The coastal lowlands rarely extend in excess of 50 kilometres leaving the ports with limited agricultural hinterlands (Caro Baroja, 1977).