 The municipality in the Extoráz River basin, which receives rainfall over a surface of 2,149 km2 and results in a river that moves 1,150,000m3 of water each year.This river is the main one in the municipality, and has carved out a large canyon called the Cañon del Paraíso (Paradise Canyon), located three km west of the town of Peñamiller.This canyon is barely ten meters wide, but it is 700 meters long with sides of black marble up to one hundred feet high.