The Cavallers swamp is a reservoir belonging to the Noguera de Tor, created by a dam located in the town of Vall de Boi, in the Alta Ribagorça. The dam was built in 1960. It is located 1784 m above sea level and its dam, 70 meters high and 360 meters long is the type called buttresses. At Cavallers swamp has their origin the river Noguera de Tor, 24 km long from the Vall de Boí, crossing the towns of Caldes de Boí, Erill la Vall, Barruera, Llesp and Castilló de Tor and ending in the river Noguera Ribagorçana at the end of the town El Pont de Suert.