Castro-Urdiales has a population of approximately 33,000 people. The city’s population is diverse, with a mix of local residents and a growing number of expatriates, particularly from nearby regions such as the Basque Country. The population tends to increase during the summer months when tourists and seasonal visitors arrive, boosting the local economy.
In recent years, the city has seen moderate population growth, driven by its appeal as both a tourist destination and a desirable place to live for those seeking a quieter lifestyle away from the larger cities. The local community is friendly and welcoming, with a strong sense of tradition and cultural pride.