The Catalan Pyrenees form a unit of relief that acts as a natural border. They are made up of different natural parks of great beauty and especially protected for their richness in fauna and flora. Among the natural parks that we can find in the Pyrenees, theese are some of the most relevant: Cap de Creus Natural Park, Les Capceleres del Ter i del Freser Natural Park, Cadí Moixeró Natural Park, Alt Pirineu Natural Park, Aiguestortes National Park i Estanys de Sant Maurici, Poset-Maladeta Natural Park, Ordesa and Monte Perdio Natural Park.
The total extension of the Pyrenees is 400km. The long-distance trail or GR that crosses the Pyrenees is the GR11 and has an extension of about 800km. It crosses all the Pyrenees from the Atlantic Ocean (Cabo Higuer) to the Mediterranean Sea (Cap de Creus).
In the Catalan Pyrenees there are more than 400 lakes. The largest of all is the Certascan in Pallars Sobirá with more than 100 meters deep.