Lake Bolsena is the largest lake in the northern part of the region of Lazio in Italy and the largest volcanic lake in the whole country, having a circumference of 43km. It is known for a strange phenomenon, known locally as “sessa”, which causes tidal-like movements in the lake. Its formation began 370,000 years ago following the collapse of a caldera of the Vulsini volcano, which stayed active until 104 BC. The two islands in the southern part of the lake were formed by underwater eruptions.
By car Lake Bolsena can be easily reached from Rome by taking the Cassia bis road. It can also be reached from the main A1 tollway (Autostrada) that connects Rome and Florence, by exiting at Orvieto.
The towns of the lake are served by buses that depart from the bus station at Viterbo.
There are several places where it is possible to go swimming in the lake.
Lots of restaurants close to the lake offer dishes cooked with fish from the lake. Well worth trying. Dishes of eels from the lake may also be available.