Predil/Raibl glacial lake is located near the former mining settlement of Cave del Predil/Rabelj/Raibl below Predil/Predel mountain pass which lies on the state border between Italy and Slovenia. The lake at an altitude of 959 metres with 1 km2 of surface is surrounded by the Julian Alps. Measuring 1,400 metres in length and 400 metres in width, it is the second largest natural lake in Friuli-Venezia Giulia. The maximum depth is around 35 metres. The surface of the lake has been decreasing because of the torrential gravel deposit.
During the summer, the lake is an ideal retreat place from high temperatures. The water is refreshing, but warm enough for swimming and different water-sports activities.
The Austro-Hungarian forts by the lake or in the vicinity of the lake still testify to the importance of the road Tarvisio/Trbiž/Tarvis–Predel/Predil Mountain Pass–Bovec Basin and the road from Cave del Predil/Rabelj/Raibl to Sella Nevea. The forts were built in the second half of the 19th and at the beginning of the 20th century by the Austrians as a result of the increasing tension between the Kingdom of Italy and the Austro-Hungarian Empire.