Lake Bolsena

Lake Bolsena, also known in Italian as Lago di Bolsena, is a large lake in central western Italy. It is in the northern part of the province of Viterbo, an area called Alto Lazio or Tuscia.

This lake is special because it is the largest volcanic lake in all of Europe.

The lake was formed by an old volcano called the Vulsini. Roman records show that this volcano was active a long time ago, but it has been quiet ever since. Two small islands in the southern part of the lake were created by underwater eruptions after the land sank down.

Lake Bolsena has a rich history. The Romans named it Lacus Volsinii, after the Etruscan city of Velzna. Many important historic sites are near the lake, and today it is a popular place for tourists to visit. One interesting fact is that part of the lake was given to the Catholic church by a noble family. In return, the family was honored by the Bishop of Orvieto.

Geography

Lake Bolsena has an oval shape, like many crater lakes, with its longest part running north to south. The lake’s bottom is shaped like a cone, with the deepest point in the center. Hills surround the lake, and towns sit on their slopes and peaks.

The northern hills are the tallest, reaching up to 702 meters, about 305 meters above the lake. The town of San Lorenzo Nuovo sits on the northern edge. Bolsena lies on the northeast shore, with Orvieto a bit further northeast. On the southeast side is Montefiascone, and to the south is Marta, the only place where water leaves the lake. The southern shore is straight and has buildings close to it. Nearby are the towns of Valentano and Capodimonte. Farther south are Tuscania and the regional capital, Viterbo.

North of Valentano is the Latera caldera, a smaller crater with Lake Mezzano at its western end. The area around Lake Bolsena’s western hills is rough and mostly used for farming, with some rocky areas left wild. Grotte di Castro and Gradoli sit on the western edge of the northern hills.

Geology

Main article: Vulsini

Lake Bolsena is in the Vulsinii Volcanic District. The lake formed when a round area sank down. This happened after the underground magma chamber that fed the volcanoes emptied out. Even though it is called a volcanic lake, it is not inside a crater or a caldera like some other lakes. Big calderas, which are large sunken areas from old volcanic eruptions, are near the edge of the lake.

Islands

Bisentina

Bisentina is the biggest island in Lake Bolsena. It is 17 hectares or 42 acres. You can get there by ferry from Capodimonte. The island has lovely evergreen oaks, Italian gardens, and some important buildings. There is a church for Saint James and Saint Christopher, a Franciscan convent, and a small temple named the Rocchina for Saint Catherine.

The island also has a historic chapel with old paintings and a spot called Malta dei Papi, where water was once stored. Over time, many different people lived there.

Martana

Martana is another island in the lake, close to the town of Marta. Long ago, it was thought to keep important things safe from attackers. Today, the island is private and not open to visitors.

Marta outlet

The Marta is a river that takes water from Lake Bolsena to the east. It begins near the town of Marta and flows through Tuscania and Tarquinia before reaching the Tyrrhenian Sea. Near the sea, people have made special places for producing salt.

Comuni bordering the lake

The following towns are located along the shore of Lake Bolsena:

• Bolsena
• Montefiascone
• Marta
• Capodimonte
• Valentano
• Gradoli
• Grotte di Castro
• San Lorenzo Nuovo

Each town has a special beach area where people can swim during the summer. Some of these towns also have nice places to eat, drink, and rent boats.

Other nearby towns include Sorano, Pitigliano, Acquapendente, Orvieto, and Onano to the northwest.

Films

The show Tucci in Italy showed Lake Bolsena in Season 1, Episode 5. That episode aired in 2025.