The longest navigable underground river in Europe is in Spain. Specifically, in the Vall d’Uixóa charming municipality in the province of Castellon. We are talking about a unique natural jewel: the Caves of San José (Coves de Sant Josep in Valencian).

This spectacular site is home to the longest navigable underground river in Europe, allowing visitors to explore the depths of the Sierra de Espadán through a path traced by water for millennia.

A unique and prehistoric natural enclave

The Coves de Sant Josep not only offer a privileged underground landscape, but are also a significant cultural enclave. At the entrance of the cave, as reported on the Vall d’Uixó Tourism website, you can admire unique prehistoric paintings and engravings dating back more than 15,000 years, belonging to the Upper Paleolithic. The surrounding area includes the Iberian town of Sant Josepa visitable archaeological site located at the top of the hill next to the baroque hermitage of the Sagrada Familia.

Coves de Sant Josep (Vall d'Uixó, Castellón)
Coves de Sant Josep (Vall d’Uixó, Castellón)

To enter this mysterious underground world, visitors can enjoy a boat ride of 800 meters and a walk of 250 meters through a dry gallery. The experience, guided by an expert boatman, has a approximate duration of 45 minutes and it can be done all year round thanks to the constant temperature of 20ºC inside the cave. The price of the visit ranges between six and 14 euros per person depending on age.


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SpeleoKayaking: a unique kayak adventure

Espeleokayak in the Coves of Sant Josep de la Vall d'Uixó (Castellón).
Espeleokayak in the Coves of Sant Josep de la Vall d’Uixó (Castellón).

But the exploration doesn’t stop there. For those looking for a more leisurely and unique experience, Viunature, an active tourism company in the province of Castellón, offers the speleokayak activity. This adventure combines the observation of karst formations inside the cave with the thrill of kayaking.

Different from the traditional boat visit, the kayak experience lasts approximately 2 hours and allows you to explore all the galleries of the visitable section of the underground river. Guided by professionals, small groups of about 16 people can enjoy the Crystal clear waters and unique geological formations. No prior kayaking experience is required, as a hands-on explanation is provided prior to the activity. The price is 40 euros per person.


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Singin’ in the Cave: an incredible musical experience

Singing show in the Caves of San José de la Vall d'Uixó
Singing show in the Caves of San José de la Vall d’Uixó

But Vall d’Uixó not only offers natural wonders, but also unique cultural events. Singin’ in the Cave is an annual project that transforms the Coves de Sant Josep into an unparalleled setting for acoustic concerts inside the cave.

The musicians perform live, without amplifiers, from a boat in one of the most beautiful lakes in the cave, the Bat Room. The unique resonance of the hall makes these concerts a unforgetable experience.


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Afterwards, the musicians and the public continue the concert on the pier, this time with amplified sound but still inside the cave, creating a magical atmosphere that combines music with an underground heritage unique in the world. At the moment, the three performances scheduled for March and April are all sold out.

Vall d’Uixó beyond the San José Caves

A technician from the Generalitat holds one of the ringed Bonelli's eagle specimens for monitoring.
A technician from the Generalitat holds one of the ringed Bonelli’s eagle specimens for monitoring.

Vall d’Uixó offers much more than just the Coves of Sant Josep. For example, for lovers of bird watching, the birdwatching in the Sant Josep area is an exciting activity where you can see birds of prey such as the peregrine falcon, Bonelli’s eagle and common kestrel.

For those interested in history, the archaeological site of Sant Josep, declared an Asset of Cultural Interest, offers the opportunity to travel back in time to the 6th century BC and explore the different stages of occupation, from the Iberian era to the medieval period. It has an access price of 3 euros per person.

Ibero-Roman Village (Vall d'Uixó, Castellón)
Ibero-Roman Village (Vall d’Uixó, Castellón)

In addition, the Vall d’Uixó has a trail network, such as the PR-V-164 and PR-V-241 routes, which allow you to discover Muslim towers, unique fountains, and other historical and natural vestiges.

The municipality is also home to gems such as Palau de Vivel, a palace with history that has witnessed different events over the years, from a summer residence to a blood hospital during the Civil War.

How to get to Vall d’Uixó

Church of Our Lady of the Assumption (Vall d'Uixó)
Church of Our Lady of the Assumption (Vall d’Uixó)

Getting to Vall d’Uixó by car is very simple. The city is connected to the center of the country by the A-3 and to the Mediterranean network by the A-7 and to the now free AP-7. The distance from Madrid to the Castellón municipality by road is 392.8 km. From Barcelona the distance by road is 310 km, while from Valencia it is 48 km.

If you want to travel by train, Vall d’Uixó does not have a station, but nearby towns such as Nules, Xilxes and Moncofa (8 km). There is the possibility of reaching Castellón or Valencia by AVE, AVLO or Ouigo and using a suburban train to reach the closest towns: Moncofa, Xilxes or Nules.

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