Below the Mount Perdu glaciers, at an altitude of 1600 m in the heart of the Spanish Pyrenees, the Rio Vell flows down a deep gorgebetween the vertical falls of the Visclo cnayon that is 22 km long. 33 waterfalls follow one another in a drop of one thousand metres. "The first waterfall is sinister" says the protagonist, "the water is boiling. It is a hellish slide. I don't know whether I am breathing or what my body is doing. I was bruised all over but a throng of wonderful sights are impressed on my memory. I shall never forget them".