On the Poblana plateau a mountain range rises more than 800 meters high with respect to the Valley. The Tentzo, a hill to which people confer a human appearance, is what gives this biosphere reserve its name. It crosses part of the most important river basin in the state, the Atoyac.
Declared a protected natural area, with 57 thousand 815 hectares, in 13 municipalities, represents 1.6 % of the state's surface. Due to its geographical location, climatic variation and differences in altitude, the area is home to a large number of animal and plant species, endemic and of economic importance to its inhabitants: at least 91 species of medicinal plants, 18 species of mammals, 153 species of birds, 21 species of amphibians and reptiles.
Its inhabitants and visitors participate in programs of conservation and rescue of the flora and fauna of the place; as well as in ecotourism and extreme sports activities.