The trip to Forau d’Aigualluts lets us see up close the immensity and magnificence of Posets-Maladeta Nature Park. In this natural whim, located in the foothills of Aneto peak, the water coming from Aneto and Maladeta glaciers converges and disappears underground at 2,074 meters high.

The destination of this water that plunges into this enormous drain (it has 70 meters wide and 40 meters depth) was a mystery until 1931, when finally it was proven that the water travelled underground during 4 kilometres and appeared again on the surface in Arán Valley, concretely in an area known as Uelhs deth Joeu (Jewish eyes) in aranés dialect at 1,658 meters high.

There are different routes to arrive to this magic place but the most common is the next one.

The path starts in Vado del Hospital parking lot and few minutes later arrives to Hospital de Benasque surroundings. Here, there is an ancient path on the left called Camí dels Aranesos that was used by the locals to communicate Benasque Valley with the adjacent Arán Valley (in summer, there is a bus that drives to La Besurta parking lot —located 3 km up-valley at 1,900 m, where the valley road dies—, but using it deprives visitors of visiting really interesting and beautiful areas).

Following this ancient path, you will come across the meadow of Plan d’Están with its hut reaching La Besurta at the end of it. Plan d’Están is a perfect area to look out for marmots or at least to listen to their characteristic and high-pitched whistles.  

At approximately 10 minutes of leaving behind La Besurta, you will find the junction with the path that goes up to La Renclusa mountain refuge on the right, so pay attention and follow the left-hand way.

Then, you will arrive directly to Forau d’Aigualluts viewpoint, an endokarstic drain that, like a funnel first and a natural underground canal later, gathers up the water that comes from the waterfall and sends it to Arán Valley.

The path overtakes Aigualluts waterfall on the right and continues going up to finally arrive to Plan d’Aigualluts, an idyllic and enormous meadow throughout of which the water that melts from Maladeta massif glacier twists and turns. This prairie was formed thanks to a glacier lake silting and is surrounded by an unbeatable landscape. Looking to the front-right, the Aneto summit and the glacier remainders clearly stick out, and far away you will be able to see the prismatic accumulation of soil and stones that form the glacier lateral moraine (northeast edge), something that gives an idea of the glacier dimensions during the relatively recent Little Ice Age (between the 14th and mid-19th centuries). The Aneto glacier is one of the biggest glaciers that remain in Spain and it belongs to the ensemble that has been declared to be of Pyrenean Glaciers Natural Monuments.

This trail corresponds to the Geomorphological Trail. Benasque Hospital Plains - Forau de Aigualluts of the Posets Maladeta Natural Park