The Gresso river is a tributary of the Vouga and originates in the Arestal mountain range, at almost 800m altitude.
It is a mountain river that runs 7 km along its descent to the mouth, with a difference in level of more than 700 meters. For this reason, there are several waterfalls and waterfalls that have little flow in summer, but fill up with winter rain.
Two waterfalls stand out along this river, Moinho Velho and Cascata do Gresso or Escarpa do Gresso. Walking the trail leads us to the discovery of a shady forest with a very closed and private riparian gallery.