Pozo de los Humos Nature · Masueco, Vitigudino, Salamanca The Pozo de los Humos is a waterfall on the río de las Uces, on the boundary between Masueco, on its left bank, and Pereña de la Ribera, on the right, in the northwest of Salamanca province, within the Arribes del Duero natural park. It originates at an abrupt change in the rock caused by a geological fault that brings granite into contact with more erodible metamorphic rocks; the river plunges down a granite wall in a free fall of fifty metres that, on reaching the bottom, raises a cloud of vapour, hence its name. From Masueco, along the slope of the Roblea, a walkway leads to the top of the waterfall, opposite Palla Rubia, in Pereña, where a cave preserves rock art. The flow suitable for visiting it runs from December to May and, according to local tradition, it has never snowed there. Photo: Arribeño (CC BY 3.0) What to see and do in Masueco