Lake Vico is a caldera lake in the northern Lazio region, central Italy. It is one of the highest major Italian lakes, with an altitude of 510 m. Administratively, it is part of the municipalities of Caprarola and Ronciglione.
The lake is surrounded by the Cimini Hills, in particular by the Fogliano and Venere mountains. It is part of the Lake Vico Natural Reserve.
According to legend, the lake was created by Hercules, who defied the local inhabitants by wielding his club. When he did this, a stream sprang up and formed the lake.
Lake Vico occupies the central caldera of Vico Volcano. A volcanic cone was built up in a series of eruptions that occurred 305,000 to 258,000 years ago. Later, the eruption of voluminous pyroclastic flows, and volcanic ash, caused the progressive collapse of the volcanic cone, which created the caldera, in which Lake Vico now lies, by about 138,000 years ago.
The lake is drained by the River Vicano. Before the construction of a tunnel by the Etruscans, the lake was probably deeper than today, the Monte Venere constituting an island within it.
The area is famous for its extensive Beech forest, which is one of the most southerly in Europe.