Lago di Cavazzo or lago dei tre comuni is the largest natural lake of Friuli Venezia Giulia. It is 9 km long, wide from 400 to 800, 50 metres deep and has an area of 1.74 km ². Is located in the municipalities of Bordano Cavazzo Carnico and Trasaghis. Of glacial origin, is 191 metres above sea level, below the Tagliamento River that flows about 3 km to the East. In the winters freeze to the surface.