Isla de la Deva and Playón de Bayas Nature · Soto del Barco, Avilés, Asturias A natural monument declared by Decree 20/2002 of the Government of Asturias that protects the Playón de Bayas, the longest sandy stretch in central Asturias, alongside the cliffs of Punta Socollo, and the Deva, the largest island in the Principality, east of the mouth of the Nalón river, between Castrillón and Soto del Barco. Almost three kilometres long, the Playón de Bayas was formed by sediments carried by the Nalón, moved by littoral currents until they formed an extensive dune system, interrupted only by the Fontebona stream. Protected species grow on its dunes, such as the sand spurge, present in barely two other Asturian localities, along with marram grass and sea daffodil, as well as rock-dwelling vegetation and colonies of seabirds. Photo: Bermiego (Wikimedia Commons) (CC BY-SA 3.0) What to see and do in Soto del Barco