Playa de Arenillas, Beach in Castro Urdiales, Spain
Playa de Arenillas is a small beach in Castro Urdiales extending 50 meters along the Cantabrian coast with fine sand and silt deposits. The shoreline features a mix of sandy sections and muddy banks that shift with tidal changes, creating varied surfaces across its 15-meter width.
The name Arenillas derives from "Arna", not from "arena" (sand), so the original toponym was Arnillas. The cove lies at the foot of a powerful cliff that links it toward the beach of Oriñón, in the municipality of Castro Urdiales. At the highest tides the sea covers it completely, and at low tide it leaves a space among the rocks.
The name Arenillas does not come from arena (sand) but from Arna, so the original toponym is Arnillas. The cove is frequented by nudists, a use that has become part of its local identity.
Basic facilities including showers and waste bins are available, and the beach is free to visit. Walking paths connect it directly to central Castro Urdiales, making it easy to reach on foot without needing transport.
The name Arenillas does not come from arena (sand) but from the root Arna, so the original toponym is Arnillas. At the highest tides the beach vanishes entirely, and at low tide it opens a space among rocks beneath a cliff that links it with the beach of Oriñón.
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