The Pas de l'Ase” gorge is a space where the Ebro River makes its way between the Picosa and Tormo mountains. It can be accessed thanks to old trails such as those of “Sirga” or “Mulas” (Towrope or Mules), which give them their names, employed many years ago for the transport of goods along the course of the river. Due to the narrowness of its route, the riverbank forest is dominated by the waters that make their way between vertical walls