Lake Bolsena: The Lake You Can Drink

Lake Bolsena is the largest volcanic crater lake and the 5th largest lake in Italy. It is sometimes called Italy’s bellybutton because of its location and oval shape.

Lake Bolsena Stats

Lake NameLake Bolsena
Surface area113.440
Maximum depth151.0
Average depth18.3
Lake typeVolcanic
Catchment area282.70
IslandsBisentina, Martana
Shore length46.88
Residence time7643.2
Average discharge3.151
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Formation and Geology

Lake Bolsena, located in the center of Italy, started to accumulate 370,000 years ago, after a caldera was formed in the Vulsinii volcanic complex. Bolsena is located in the middle of the Vulsinii Volcanic District of the Roman Comagmatic Region. Scientists affirm that the last time the volcano erupted was in 104 BC, and has been dormant ever since. At least four volcanoes were active around Bolsena when the lake formed, called Latera, Montefiascone, Bolsena and Capodimonte. Two large islands, Bisentina and Martana were created as a result of underwater eruptions.


Lake Bolsena, located at 305 m altitude, is surrounded by 600-650 meter high hills. San Lorenzo Nuovo lies on the northern rim of the caldera. It was moved there from a more southern place, to avoid malaria which was caused by the mosquitos living in marshes in the lake’s northern shores. These marshlands are now used in agricultural purposes.

Orvieto is located 14 kilometers to the north-east, at the edge of the volcanic region. In the south-east Montefiascone is located, right on the ridge of the caldera with the same name. Marta can be found on the right bank of the Martana River. Valentano and Capodimonte lie close to Marta. The latter was constructed around the only headland on the lake, forming a protective harbor. Gradoli, Sorano, Pitigliano, and Acquapedente are other communities surrounding the lake, set on the border of Tuscany and Lazio. Viterbo, the capital of Lazio is 15 kilometers to the South.

The lake has an oval shape with an axis of ellipse leading from North to South. Its bottom is mainly canonical and the maximum depth of 151 meters can be found approximately in the middle of the lake. The floor of the caldera is used mainly for agricultural purposes, except for the uncultivable rocky areas which remained forested.

Hydrology and Climate

Lake Bolsena is supplied from aquifer, rainfall and runoff. It has only one outlet, the Marta River, which makes its way into the Tyrrhenian Sea, reaching it at Lido di Tarquinia. Salt pans have been built between the Marta’s mouth and that of the Mignone River. Bolsena is known for a strange phenomenon called “sessa”, which causes a kind of tidal movements in the waters. The maximum difference of the high and low tides is said to be 50 centimeters.

Bolsena is situated in an area with mild climate. Its summers are usually dry and warm. July and August are the hottest months, when temperatures can reach up to 35-40OC. During the hot summer siesta time is held every day between 1-4 pm, when everything is closed. Winter averages are between 3-5OC. Spring and autumn temperatures are between 18-25OC, making it the perfect time to visit Lake Bolsena.

History and the Miracle of Bolsena

The Romans called the lake “Lacus Volsinii”, adapting the Etruscan name “Velzna”, which was one of the last Etruscan cities to hold out against the Roman conquer. The city was relocated in 264 BC and its original location is not known today.

In 1263 a bohemian priest called Peter of Prague went on a pilgrimage to Rome to intensify his faith in God. He made a stop at the Saint Christina church of Bolsena to attend the local Holy Mass. During the service he noticed blood leaking from the consecrated host. It dripped over his hands, onto the marble altar and corporal. The priest interrupted the mass and asked to be taken to the then-pope, Urban IV, to Orvieto.

After he told the story to the pope, the religious leader requested that the linen cloth and host to be brought to Orvieto. Pope Urban IV deposited the religious relics in the cathedral and was inspired by this miracle to commission Saint Thomas Aquinas to compose the Proper for a Mass and an Office, in honor of the Holy Eucharist, as the Body of Christ.

A year later, in August of 1264, the pope introduced the saint’s composition and inaugurated the feast of Corpus Christi. The linen and holy corporal are still in Orvieto in a golden shrine, but the reliquary containing the marble stained by blood can be seen in the cathedral of Bolsena.

One-third of the lake was donated to the Catholic Church by the wealthy Alberici family of Orvieto, who were, in return, recognized and honored with a ceremony held three times each year by the Bishop of Orvieto.

Bisentina and Martana Islands

Bisentina is the larger of the two islands located on Lake Bolsena and can be accessed with a ferry ride from the town of Capodimonte. There are plenty of historical buildings on the island, including the Saint James and Saint Cristopher church, with its cupola constructed by Jacopo Barozzi da Vignola. A Franciscan convent, a small temple dedicated to Saint Catharine (the Rocchina) can also be found among the groves of evergreen oaks and the beautifully arranged Italian gardens. The chapel of the Crucifix is also located on Bisentina, with impressive frescoes dating back to the fifth century.

The island itself has a tumultuous history. In the 9th century it served as a refuge from the invasion of the Saracens. In 1250 it became the property of the lord of Bisenzio, who abandoned the precinct and attempted to burn it down after disagreeing with the locals. The area was once again destroyed by Louis the IVth of Bavaria in 1333. In 1400 the island became the property of the Farnese family, during which the area prospered and was frequented by many religious leaders. It’s currently owned by Beatrice Spada Potenziani, the wife of Duke Fieschi Ravaschieri.

The island of Martana lies opposite to Marta town and cannot be visited, because it is privately owned. The island once protected the relics of Saint Christine from Barbarians and is said to be the assassination place of the gothic queen Amalasuntha.

Tourism and Leisure

Lake Bolsena is considered to be an unspoiled paradise surrounded by captivating medieval towns, ancient ruins, friendly locals, cypress forests and a fruitful countryside. Even though it has its perks, it is away from the tourist hotspots, making it a less-crowded holiday destination. The lake is a popular target among those searching for the more authentic side of Italy.

Because it is surrounded by many hills, it is often considered hiker’s heaven, offering scenic views and trails that range from easy to challenging. There are also many cycling paths for mountain bikers on the hills, and there are easier routes on the coastline. Two famous pilgrimage routes are close-by, connecting Rome and Siena: the Via Francigena and the Via Casia.

Although a fishing permit is needed, fishing is still a favored activity. The region’s most famous fish is the coregone trout, which is preferred because it has few bones and a mild flavor. Pike, perch, eels, mullet, ghiozzo, core gone and zander can also be found in the waters of Lake Bolsena.

Motor boating, waterskiing, sailing and surfing are the most frequented water sports activities. Sailing boats and catamarans can be rented from local shops. There are also two sailing schools on the northern end of the lake, and a few horse-riding schools just outside Bolsena. A number of swimming beaches can be found in nearly every town located on the lakeshore. The water is said to be so clean, Bolsena is nicknamed “the lake you can drink”.

The Lake Bolsena area is also considered to be a bird-watcher’s paradise, since black redstarts, red crested pochards, coots, great crested grebes, egrets and grey herons can be found here.

Lake Bolsena Map