The lake of Alleghe lies in the high Val Cordevole, and is dated back to 1771. It is a typical Alpine lake since its formation is due to a landslide on a layer of the Monte Forca, which rises in front of the village of Alleghe. Nowadays, only the lower part of that layer, called Monte Piz, is existent and it is still possible to see the great mutilation, which gave origin to the Alpine lake. 11 January 1771 a huge landslide fell from Monte Piz and buried the villages of Marin, Riete and Fusine.
The colossal barrier made of debris, stopped the waters of the river, which rose up to it and then took again its course. Rising, the waters gave origin to the present lake that in only three days became 35 deep and half a mile long, flooding the villages of Sommariva, Torre, Costa, Peron. Alleghe, being in a higher point, could be saved from the disaster. Nowadays the lake represents one of the best characteristics of the area with its peculiar attractions, among which there are fishing, windsurfing, canoeing, sailing, and the possibility of renting a boat to pass a pleasant and relaxing day.