Estany Negre (Black Lake) of Boí Nature · la Vall de Boí, Alta Ribagorça, Lleida The Estany Negre, also known as Negre de Caldes, is a lake of glacial origin located at 2,134 metres above sea level in the municipality of the Vall de Boí, within the Aigüestortes i Estany de Sant Maurici National Park, at the head of the Caldes valley, at the entrance to the Colieto valley. It covers 9 hectares and reaches a maximum depth of 35 metres; it receives the waters of the Estany de Colieto and drains via the Riuet d'Estany Negre stream. It lies at the foot of the walls of the Pics de Comalespada and the Agulles de Travessani, above which stands the Joan Ventosa i Calvell refuge, from where there are views of the Besiberri massif. The most usual route to reach it starts from the Cavallers dam, via the Pletiu de Riumalo, the Barranc de les Llastres and the Pas de l'Ossa. Photo: Josep Borrut (CC BY-SA 3.0) What to see and do in la Vall de Boí