Castro Urdialis was founded by the Romans and is a popular tourist destination today. It offers a sports harbour, a fishing harbour and two beaches. Beach Brazomar is east of the town center. Beach Ostende is longer and is west of the town center. In August these two beaches are typically crowded.
In the center of the town are the city hall surrounded by a square. Close to it, right on the ocean, are the light house and the church.
Castro Urdiales is easily reached via the A8 freeway from Bilbao (about 35km) and from Santander. Public transport buses go to Bilbao every 30 minutes and cost €2.82. Santander is roughly an hour by bus and buses go to Santander every 1-2 hours. The closest airports are Bilbao and Santander.
Castro is small enough that you can walk nearly everywhere. The furthest distance is to walk from Brazomar Beach to Ostende Beach. This is about 2-3km and takes accordingly 30-45min of walking.
Light house, church, town hall, beaches
Sun-bath in summer, stroll along the beach promenade, sit in one of the many coffee bars along the water front.
Sea food, grilled sardines
There is number of good cider bars in town.