Mongayo Waterfall Nature · Caso, Nalón, Asturias A waterfall of about 60 metres formed by the Mongayu stream in the cut of a glacial cirque, reached by a path starting at Tarna and crossing the Monte Saperu beech forest. It was declared a natural monument on 22 May 2003. It lies within Redes Natural Park, near the village of La Campona, and before the park's second PRUG (Management Plan) declaration opened up access, a permit had to be requested at the interpretation centre in Campo de Caso. Shortly after starting the route, a detour leads to the Rebollos de Llanu'l Toru, two large Pyrenean oaks with a trunk twenty metres in circumference standing at the heart of the forest; the main path continues to the foot of the waterfall, also known as the Taballón waterfall. Photo: Eduardo Diez Viñuela (CC BY-SA 3.0) What to see and do in Caso