A complete guide to caves and grottoes in Italy: Frasassi, Castellana, Grotta Azzurra Capri, Grotta Gigante Trieste, Nettuno Alghero. Prices, hours, how to get there.
Italy is one of the nations with the highest density of caves in the world: over 35,000 catalogued cavities (data from the SSI, the Italian Speleological Society), distributed mainly in the limestone areas and on the marine coasts. Not all are visitable, of course. But the Italian tourist caves include some of the most spectacular sites in Europe, with an offering that ranges from the tiny marine grotto of Capri to the underground cathedral of Frasassi.
The Frasassi Caves, in the municipality of Genga (AN), contain the largest underground hall in Europe: the Sala Grande del Vento, with dimensions of 240 m x 120 m x 80 m high, big enough to contain Milan Cathedral with its tallest spire. Discovered in 1971 by speleologists of the Fabriano CAI, who lowered themselves into the hall for the first time through a hole in the ceiling of the mountain.
The Frasassi system extends for over 30 km of galleries (the tourist part is 1.5 km). A constant temperature of 14°C. Stalactites, stalagmites, and aragonite formations of exceptional dimensions. The tourist route is paved and lit, accessible even to those with no caving experience. Visit duration: 75-90 minutes.
The Castellana Caves, in the province of Bari, are the most important underground attraction in Southern Italy. The system has a development of 3,358 meters, the longest karst complex in the South. The high point is the Grotta Bianca, a hall entirely covered with white calcite crystals, one of the whitest caves in Europe.
The cave was discovered in 1938 by the speleologist Franco Anelli, who descended into an abyss known locally as "La Grave" (the cave), used by farmers as a dump for centuries, unaware of what was below. It took two years of work to open the tourist route, inaugurated in 1950 by Alcide De Gasperi.
The Grotta Azzurra di Capri isn't the largest nor the most spectacular geologically. It's the most famous for the optical phenomenon that makes it unique: the light enters from the submerged opening on the bottom (1.2 m below the surface) and refracts through the turquoise water, illuminating the interior with an intense blue reflection that colors everything it touches blue, boats, guides, visitors.
The opening is 1 meter high from the water's surface, you have to lie down on the little boat to enter. The interior dimensions: 54 m x 30 m, maximum height 15 m. It isn't a place for the claustrophobic. The official "discovery" is from 1826 (the German painter August Kopisch and the entrepreneur Ernst Fries), but the Romans knew it well, the emperor Tiberius had built an internal landing stage.
The Grotta Gigante in Trieste (municipality of Sgonico, TS) holds the Guinness record for the largest single tourist hall in the world: 107 m x 280 m x 98 m high. For a parameter: the Dome of St. Peter's in Rome (height 136 m) would fit inside without touching the ceiling. Discovered in 1840, opened to tourism in 1908, it's one of the oldest tourist caves in Italy.
The cave is in the Trieste Carso, the karst plateau that gives its name to all the "karst" formations in the world (karst in English comes from Carso). The limestone substrate of the Trieste Carso, formed in a marine environment in the Cretaceous (65-145 million years ago), was shaped by rainwater acidified by CO2, the same process that creates all the limestone caves in the world, only more spectacular here.
The Grotta di Nettuno is a marine cave on the promontory of Capo Caccia, 20 km from Alghero. A development of over 4 km, but only 200 m open to tourism. The interior is exceptional: calcite columns up to 10 m high, internal lakes, a formation called "Maccheroni" for its curious shape. The main hall is 60 m wide.
Accessible in two ways: by boat from Alghero (30 minutes of navigation, sea permitting, €15) or by going down on foot the Escala del Cabirol, 654 steps carved into the rock of the promontory. The name "cabirol" means roe deer in the Algherese dialect, the staircase is as steep as the leap of a roe deer. Going down: 20 minutes. Going up: 35-45 minutes. Not recommended with inadequate footwear or heart problems.
| Cave | Region | Special feature | Adult price |
|---|---|---|---|
| Grotta del Vento | Garfagnana (LU) | 3 routes, 2h the longest | €12-20 |
| Grotte di Toirano | Savona (LG) | Paleolithic, Ursus spelaeus prints | €13 |
| Grotta Bue Marino | Dorgali (NU) | Boat only, historic monk seal | €15 |
| Grotte di Pertosa | Salerno (CA) | Boat on the internal water | €13 |
| Grotta di Ispinigoli | Nuoro (NU) | 38 m stalagmite, the tallest in Europe | €12 |
| Grotte di Equi Terme | Massa-Carrara | Cave bear, adventure route | €10-15 |
The longest cave system in development is the Abisso di Bifurto (Pollino, Calabria) with over 60 km of galleries, but it isn't a tourist cave. Among the tourist caves, Frasassi has the largest hall (Sala Grande del Vento) and Castellana has the longest system open to the public (3.3 km). The Grotta Gigante in Trieste has the largest single tourist hall in the world.
Stalactites grow from the ceiling downward, stalagmites from the floor upward. Both form by the deposition of calcite (CaCO3) from water percolating through the limestone. Rainwater, slightly acidic from the dissolved CO2, dissolves the limestone and transports it. When the water arrives in the cave and loses CO2, the calcium carbonate precipitates. Growth rate: 0.1-10 cm every 100 years, it varies enormously based on the amount of water and the calcium concentration.
The Italian tourist caves are completely safe, lit, paved routes, with mandatory guides in many cases. Zero risk is guaranteed for the standard tourist routes. It's a different matter for caving in unequipped caves, an activity that requires specific training, adequate equipment, and is never improvised. If you want to approach caving, contact the CAI (Italian Alpine Club), which organizes courses throughout Italy.
The Italian caves are visitable year-round, a constant internal temperature between 11°C and 18°C regardless of the external season. In summer they're a pleasant escape from the heat. In winter they're therapeutically warm. The problem isn't the internal climate but the crowd: July-August is the worst period for queues and bookings. September-October is ideal: fewer tourists, the same experience.
For those who want to go beyond tourism: the Italian Speleological Society (www.ssi.speleo.it) coordinates the exploration activities and has sections in every region. The deepest caves in Italy are in Friuli-Venezia Giulia (Abisso Michele Gortani, -920 m) and in Calabria (Bifurto, -850 m). Italy is in 4th place worldwide for the depth of the explored caves.
The Italian tourist caves have a constant temperature between 11°C and 18°C, always colder than outside in summer, always warmer in winter. Bring an extra layer (a light jacket) even in midsummer, especially for the colder caves like the Grotta Gigante (11°C) and Frasassi (14°C). Closed, non-slip-soled shoes are mandatory, the cave floors are damp. High heels are prohibited in most Italian caves.
It depends on the age. Most Italian tourist caves are suitable for children aged 4-5 and up. The routes are paved and lit. Small children often get bored on the long routes (2+ hours), better to opt for the short routes. Frasassi has a short 1 km route perfect for families. Castellana offers tours of different durations. The Grotta Azzurra di Capri isn't recommended for children under 6 because of the lying-down entry on the boat.
In most Italian tourist caves photography is allowed but flash is often prohibited (it disturbs visitors and can damage delicate formations). Some caves prohibit photography for commercial reasons (they sell postcards and official photos). Check first. For the Grotta Azzurra, the natural light at the entrance is enough for photos at ISO 1600-3200, you don't need flash and it would be counterproductive anyway in such a small space.
The Italian Speleological Society (SSI) coordinates Italian caving with 200+ local groups across the Peninsula. The basic caving courses typically last 4-6 weekends and cost €150-300, they include safety notions, rope descent, and underground orientation. The CAI (Italian Alpine Club) has caving sections in many cities. The free-access (non-tourist) caves are catalogued in the National Register of Italian Caves (www.catastogrotte.it), a database of over 35,000 cavities. To explore unequipped caves a flashlight isn't enough: you need a helmet, a harness, ropes, knowledge of vertical-progression techniques. Never alone, never without telling someone outside your route.
1. The microclimate of caves really treats asthma. Speleotherapy, therapy in an underground environment, is practiced in some Italian caves (the Grotta di Pietraroja, BN; some thermal baths in Alto Adige) to treat asthma and chronic bronchitis. The theory: allergen-free air, controlled humidity, and a constant temperature reduce bronchial inflammation. The scientific evidence is limited but some studies support the effectiveness for the mild forms of allergic asthma.
2. Caves are precision scientific instruments. Stalactites and stalagmites are exceptional climate archives, their layers grow in proportion to the rainfall and temperatures of each year, like the rings of a tree but more precise. The research group of the University of Trieste dated Italian climate events of 200,000 years ago by analyzing Frasassi formations with uranium-thorium.
3. Castellana inspired Dante. Local tradition (undocumented but persistent) holds that Dante Alighieri visited the Castellana area before writing the Divine Comedy and that the "Bolgia of the Diviners" of the Inferno is inspired by the Apulian caves. Impossible to verify, but the Castellana Cave hosted a theatrical show of the Comedy for years, "La Divina Commedia Opera Musical," in its underground spaces.
4. The Grotta di Nettuno had another story. Before the tourist opening in 1954, the Grotta di Nettuno was used by the fishermen of Alghero to preserve the catch, the constant temperature of 14°C was a natural refrigerator. The shepherds of the Capo Caccia area knew it as "Sa Covaccia de Nettunu" and brought their flocks there during the hottest summers.
5. The cave bear hasn't disappeared entirely. The bones of the cave bear ( Ursus spelaeus ) are found in dozens of Italian caves, the Grotte di Toirano (SV) is the richest site, with Ursus spelaeus prints in the hardened mud. The species went extinct about 24,000 years ago, but its DNA is found in modern Italian brown bears, confirming the interbreeding that occurred during the coexistence of the two species.