On its course through the province of Zaragoza, the River Piedra and its tributary the River Mesa pass through the limestone ravines and canyons which they have persistently been shaping over the years, near Torralba de los Frailes or Jaraba and Calmarza. As it passes alongside the famous Monasterio de Piedra, the river forms a beautiful nature park, where water is recreated in waterfalls and backwaters of great beauty.

Further to the north we find the Nature Reserve of the Gallocanta Lake, the largest inland lake in Spain, an ecosystem of exceptional worth, which is home in the wintertime to a large part of the European crane population. Over 200 species live in this ornithological paradise, including waterfowl and steppe birds.