Parque Natural de las Dunas de Liencres

The Parque Natural de las Dunas de Liencres stretches across 1,753 hectares of Cantabria's central coastline, covering parts of the municipalities of Piélagos, Miengo and Santa Cruz de Bezana. What began in 1986 as a 195-hectare protection focused on the dune system at the mouth of the River Pas was expanded in 2021 through Law 2/2021, which incorporated the Costa Quebrada stretch into a single protected area. The result is a natural park encompassing mobile dunes, quartzite and limestone cliffs, an estuary, salt marshes and beaches along roughly 10 kilometres of unbroken coastline.

The original dune system, on the right bank of the Pas estuary, is the feature that prompted the initial designation. Of the 195 hectares in the dune core, about 140 are reforested maritime pine (Pinus pinaster, planted between 1949 and 1973) and 33 are dunes proper, reaching heights of up to 20 metres in the most developed sectors. The dunes remain active: north-westerly winds carry sand inland from the beach, forming embryonic dunes on the seaward edge that mature into white and then grey stabilised dunes. Ammophila arenaria anchors the crests with its root system; further back, Crucianella maritima and Euphorbia paralias colonise compacted sand surfaces.

Valdearenas beach, the park's main strand, runs for over 1,500 metres of fine golden sand. It is ranked among Cantabria's longest beaches and holds environmental quality certifications during the summer season. Beside it, Canallave beach faces northwest and takes the brunt of the Cantabrian swell, making it a regular surfing spot. The inlet between the two beaches offers more sheltered water, suitable for swimming with children. The scent of salt and maritime pine that fills the path through the dunes is one of the most distinctive sensory experiences along this stretch of coast.

The Pas estuary, at the park's eastern edge, serves as a feeding and resting ground for migratory wading birds. Common sandpipers, Kentish plovers, grey herons and spoonbills gather on sandbanks exposed at low tide, particularly between September and April. The estuary forms part of the Cantabrian ZEPA network. Salt-marsh sectors host Salicornia and Spartina, halophytic plants that sustain the intertidal food web. The Pas riparian woodland of alder, willow and ash connects the estuary with the agricultural interior of Piélagos.

Costa Quebrada, incorporated since 2021, adds coastal geology of considerable interest: marine abrasion platforms, natural rock arches and coves set between quartzite walls. The Mouro and Covachos islets, opposite Covachos beach, are accessible on foot during the lowest tides and support colonies of yellow-legged gulls and European shags. This combination of dune, estuarine and rocky-cliff ecosystems in a compact area makes the park a leading resource for interpreting Cantabrian coastal dynamics.