Bracciano, Italy

Lake Bracciano (Italian: Lago di Bracciano) is a lake of volcanic origin in the Italian region of Lazio, 32 km (20 mi) northwest of Rome. It is the second largest lake in the region (second only to Lake Bolsena) and one of the major lakes of Italy. It has a circular perimeter of approximately 32 km (20 mi). Its inflow is from precipitation runoff and percolation, and from underground springs, and its outflow is the Arrone.

The lake owes its origin to intense volcanic and tectonic activity from 600,000 to 40,000 years before the present, which created many small volcanoes in the Sabatino territory. The main magma chamber was situated under the present lake of Bracciano. Its collapse created the depressed area now occupied by the lake, which is not a crater lake. Some small craters and calderas are still recognisable around the lake and in the immediate vicinity (Martignano, Baccano, Sacrofano).