Su Gorroppu is the deepest canyon in Italy and one of the deepest in Europe with one side as high as 500m (with a 300m cliff above visitors’ heads). Su Gorroppu canyon was formed over the millennia by the action of the Rio Flumineddu which, at the exit of the gorge where it has created some natural water ponds in the limestone, it is possible to find the rarest amphibian in Europe (Euproctus platycephalus). During dry months the Rio Flumineddu flows underground to emerge again when the rainfall becomes copious creating astonishing landscapes of waterfalls and pools.