The coast of Llanes is characterized by the presence of carbonated rocks which, due to the karstic process of erosion and the dissolution by seawater, they form subterranean cavities and caves over the cliffs that are filled with air. Sometimes, these cavities communicate with the surface forming vertical chimneys, from where the pressurized air is expelled producing a spectacular stream of water like a geyser (called “bufón”), accompanied by a particular sound that sounds like bellowing.
They are considered Natural Monument, because of their uniqueness, by the Protection of Natural Monuments Network in Spain. In the coast of Llanes there are various fields with “bufones” (blowholes), like the Arenillas, Santiuste and Llames. I visited the one in Llames.