The largest volcanic lake in Europe, Bolsena formed over 300,000 years ago in what is now Central Italy formed over 300,000 years ago. True to its origin it is oval shaped, with two islands and a river issuing from it. Naturally the lake is surrounded by towns with a long and rich history, such as Marta, Montefiascone, and Capodimonte. The lake is suitable for swimming and is considered one of the cleanest in Italy. Sailing and motor boats are allowed and its coast is lined with marinas, shady promenades, and beaches.