You leave Portugalete behind you with the iron Vizcaya Bridge still at your back. The first few kilometres still feel urban, but soon the industry along the river falls away and the path heads for the coast.
The hills are never extremely high. It’s just constant up and down, and it adds up. At well over 8 hours, it’s a long day for your legs. Somewhere along the way you leave the Basque Country and walk into Cantabria. Castro Urdiales sits by the sea, with a Gothic church above the harbour. You’ll see the town for a good while before you reach it: grey-blue water, green slopes and the coastline slowly opening up.