The Posets - Maladeta Natural Park was declared park in 1994 to safeguard the geomorphological formations, vegetation and flora. It is part of the Nature Network Aragon and Special Protection Area for Birds and Site of Community Importance under the EU regulations.
Comprises the regions of Sobrarbe, in the municipalities of Gistaín and San Juan de Plan and the region Ribagorza, in the municipalities of Sahún, Benasque and Montanuy.
It occupies a extesion of about 33,400 hectares with a Peripheral Protection Zone of about 5290 hectares.
It houses the largest number of peaks over 3000 m. and contains more than 95 glacial lakes with many waterfalls. Also within its boundaries include three Natural Monuments of the Pyrenean Glaciers: Massif de la Maladeta or Mountains Malditas (cursed), which highlights the Aneto (3404 m), Massif Perdiguero and Massif Posets or Llardana.
From these natural monuments are of great interest its forms of modeling glacier like moraines and mountain lakes, and karst phenomena.
One of the best ways to even observe all summits of the Park from the Aneto to Posets is using the chairlift that leaves the Ampriu, a place that is reached via the road from the town of Cerler.