Lake Bolsena

Lake Bolsena, also known in Italian as Lago di Bolsena, is a large lake in central western Italy. It is found 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 as recently as 104 BC, 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 to form the lake.

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 one third of the lake was given to the Catholic church by a noble family called the Alberici of Orvieto. In return, the family was honored three times a year 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, deepest in the center. Hills surround the lake, with towns sitting 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, moved from an older location to avoid sickness from mosquitos. 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 found in the Vulsinii Volcanic District in the Roman Comagmatic Region. The lake was formed when a circular area sank down 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 located near the edge of the lake.

Islands

Bisentina

Bisentina is the largest island in Lake Bolsena, covering 17 hectares or 42 acres. You can reach it by ferry from Capodimonte. The island has beautiful evergreen oaks, Italian gardens, and several important buildings. There is a church dedicated to Saint James and Saint Christopher, a Franciscan convent, and a small temple called the Rocchina for Saint Catherine.

The island also has a historic chapel with old paintings and a place called Malta dei Papi, which was once used for storing water. Over time, many different people lived there, including families and leaders of the Church.

Martana

Martana is another island in the lake, located near the town of Marta. It was once thought to protect important items from invaders. Today, the island is private and not open to visitors.

Marta outlet

The Marta is a river that carries water from Lake Bolsena towards the east. It starts near the town of Marta and flows through Tuscania and Tarquinia before reaching the Tyrrhenian Sea. In some places near where it meets the sea, people have built special areas for making 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 featured Lake Bolsena in Season 1, Episode 5, which aired in 2025.