Lago del Predil, Alpine lake in Friuli-Venezia Giulia, Italy

Lago del Predil is an alpine lake in Friuli-Venezia Giulia, northeastern Italy, sitting close to the borders with Austria and Slovenia. The lake lies at roughly 970 meters above sea level and is hemmed in on all sides by the peaks of the Julian Alps.

For centuries the southern border of the Imperial Duchy of Carinthia with the Venetian Domini di Terraferma ran along the crests of Predil Pass and Sella Nevea. After Venice's territory passed to the Kingdom of Italy in 1866, the Austro-Hungarian Army built a fortress on the lakeside between 1885 and 1887 to protect the road down to Tarvisio. In World War I the fort was badly damaged during the Battles of the Isonzo; some ruins remain and are open to the public.

The lake goes by three names depending on which language you speak in the area: Lago del Predil in Italian, Raibler See in German, and Rabeljsko jezero in Slovenian. This detail reflects how the surrounding valley has long been a meeting point for Italian, German-speaking, and Slovenian communities.

The lake is reached by following the road toward Predil Pass from Tarvisio, with parking available along the way. Weather at this elevation can turn quickly, so carrying a layer for wind or rain is a good habit regardless of the season.

The lake is shrinking: gravel carried down by the Rio di Saletto from Sella Nevea is gradually filling its basin. The lake is also the second largest natural lake in Friuli-Venezia Giulia after Lago di Cavazzo, measuring about 1.5 km long, 500 m wide and roughly 30 m deep.