To enter Foz, you have to cross two ancient train tunnels by foot. The first one is shorter and with bad visibility. The second one is longer and it is completely dark, so you should take a flashlight.
Once you go out of the tunnel you will find a spectacular landscape, with vultures flying over your head, the wonder of the canyon and the sound of the river.
It was declared Nature Reserve and special area for the protection of birds. It has a cobbled path, conditioned for bicycles, strollers and wheel chairs.
The parking is 2 Euros for the whole day.
15 kilometers away you will find the queen of the canyons, the Foz de Arbayún. You can visit a part of it from Usún. If you prefer, you can go to the Iso viewpoint, located on the road that goes from Lumbier to Navascués, where you have the best views of the canyon.