The 7,295 hectare Park covers approximately fifty kilometres of the most important river in Italy, following its course from Montemolino bridge up to Alviano lake, crossing Corbara artificial lake. In its Northern stretch, nearby Montemolino, the Tiber is described as “furious” because of the water impetuosity. Immediately after, nearby Pontecuti, it is called “Tever morto” (dead Tiber) because of the stream lack of speed. The most interesting and noteworthy areas are the eight kilometres where the river crosses the Peglia-Amerini Mountains ridge, shaping the Gole di Forello (Forello Canyon) biotype. It is an arduous area, scarcely affected by human activity and considered the true heart of the Park by naturalists. Birds of prey such as kites, sparrowhawks and buzzards take shelter among the foliage of holly oaks, hornbeams, brooms and heather, in the area and in the nearby Gole di Prodo (Prodo Canyion), opposite the houses of Civitella del Lago, again an arduous area, explorable by expert and equipped hikers only.
Different fauna and flora inhabit the moist areas of the two artificial lakes of Corbara (made by the Tiber embankment in 1963) and Alviano, which lushness has allowed to set up the current WWF oasis of the same name (Alviano Oasis). The approximate five-hundred hectars of moist area have become the ideal habitat for several migratory and aquatic species. Among them the Mallard duck, the Bule Heron, the Crane and even the Kingfisher.
Besides its beautiful landscape, the Park is suitable for practising the most different kinds of sports: from trekking to horse riding, from rowing to caving. Finally, the huge number of archaeological ruins from different ages make it an open-air museum, absolutely worth visiting.