Piscine Carletti

What to expect

The Piscine Carletti are Viterbo’s best-known free thermal pools: a row of open-air basins in a flat, grassy field on the city’s western edge, about 2.5 km (1.6 miles) from the centre. Locals call them le pozze, the pools. There is no operator, no ticket desk and no staff. You park on the field, walk a few steps and get in.

Hot sulphurous water rises from a spring at about 136°F58°C, close to 140°F60°C. It runs along a raised open channel and drops into a chain of basins. The small pools nearest the source are the hottest. As the water travels it cools in the air, and the larger basins at the far end sit around 86°F30°C, warm enough for a long soak in any season. Local press counted four basins in January 2025. Because fresh water flows in all the time, the pools stay warm in winter.

The setting is plain: open farmland, a big sky and no trees, so no shade. The surrounding grass doubles as a sunbathing lawn, and people bring folding chairs and umbrellas. This is a local’s swimming hole, not a spa. On a summer weekend it can be crowded and noisy. On a cold weekday morning, with steam lifting off the water, it is at its best.

The water is milky and smells of sulphur, like the nearby Bullicame. It tarnishes silver and can stain pale swimwear.

Getting there

The pools are on Strada Terme, near its junction with Strada Tuscanese, just outside Viterbo to the west.

By car from Rome: Viterbo is about an hour’s drive north of Rome. Take the SS2 Cassia, then the SS675 superstrada, and leave at the Viterbo Centro exit. Follow Strada dei Bagni and Strada Terme towards Tuscania; the pools are about 1 km past the Aeronautica Militare base. Parking is on a large free, unguarded field right beside the pools.

By bus: Viterbo’s urban buses run along Strada Terme, and the city’s thermal tourism site says a stop is a few metres from the pools. The regional line E655 stops at Terme dei Papi, about 1.5 km (0.9 miles) away on foot.

On foot: from central Viterbo it is about a 50-minute walk.

When to go

The pools are open all year, at any hour. A few times a year they are drained for cleaning and stay shut for a few days. In January 2025 the inflow stopped for several days and two of the four basins ran dry, so if a trip depends on it, check recent local news or ask in town.

Autumn to spring is the best time. The hot water feels right in cool air, and the crowds thin out. Summer weekends are busy, and with no shade the middle of the day is fierce. Go early in the morning or after sunset. Evenings and nights are popular year-round; there are no lights, so bring a torch.

Rules and etiquette

There is no entry fee, no permit and no posted rulebook. What matters:

• Swimsuits. This is a public place used by families.
• Take your rubbish home. Bring a bag. Litter has been a recurring problem here, and bins overflow on busy weekends.
• No soap or shampoo in the pools.
• Do not build or alter anything. In 2026 the Comune ordered a man who built a 23 m concrete walkway and sunbathing platform, with gutters that diverted part of the thermal channel, to remove it. Under ordinance No. 722 of October 20, 2026 he has 20 days to file a demolition plan and 90 days to restore the land, which is municipal property in an archaeological, landscape and thermal protection zone. Part of the site was placed under seizure during the case.
• Share the hot pools. They are small; move on after a short soak.

Where to stay nearby

There is no official camping at the pools, though campervans are often seen parked on the field. Viterbo, a few minutes away, has hotels, B&Bs and guesthouses, many in or near the medieval San Pellegrino quarter. Spa hotels on the edge of town, including the Terme dei Papi, offer paid thermal pools with full facilities. Montefiascone and the shores of Lake Bolsena, to the north, have lakeside hotels and campsites.

Safety notes

• Very hot water near the source. At close to 140°F60°C the spring and the first channel would scald. Keep children away from the inflow and test each basin with your hand.
• Short soaks in the hot pools. Local guides suggest 5 to 10 minutes in the hottest basins and no more than about 45 minutes of bathing overall, alternating with the cooler pools.
• Car break-ins. Thefts from parked cars are reported here. Leave nothing in sight, or nothing in the car at all.
• Footing. The ground around the pools is uneven, and local press has reported potholes. Wear sandals and bring a torch after dark.
• Head above water. Do not put your head under in untreated thermal water.
• No services. There is no first aid, lifeguard, toilet or drinking water. Bring water and keep an eye on children.

Nearby stops worth adding

The Bullicame, the free spring Dante mentioned in the Inferno, is a few minutes away on the same side of town. Terme dei Papi has a large paid thermal pool and spa close by. North of the city, the Bagnaccio reopened in 2025 as a low-cost paid park with showers and changing rooms.