Coves de Sant Josep

Coves de Sant Josep is a karst cave system in La Vall d'Uixó, in the province of Castellón, best known for hosting the longest navigable underground river in Europe. The caves are carved into Triassic-era limestone (Muschelkalk) and stretch roughly 2,348 metres, of which around 800 metres are covered by boat during the visit.

How to get there?

La Vall d'Uixó sits in the province of Castellón, close to the Costa del Azahar coastline. The cave entrance lies on the edge of town at the foot of the surrounding hills, where the underground water eventually resurfaces into the Belcaire river. Driving is the most practical option, with road connections to both Castellón de la Plana and Valencia.

What will you see?

The highlight is a ride in a small, motorless boat along the flooded underground passage. The route winds through vast chambers lined with dripstone formations — stalactites and stalagmites shaped over thousands of years. Inside, the temperature stays constant at around 20°C year-round, making the visit comfortable in both summer and winter.

Near the cave entrance, archaeologists found evidence of human presence dating back more than 17,000 years, including rock engravings and paintings from the Magdalenian period. Because of this historical and archaeological significance, the site holds Bien de Interés Cultural status, Spain's designation for assets of national cultural importance.

When to visit?

The cave welcomes visitors all year thanks to its stable internal temperature. It's worth avoiding the peak summer months (July–August), when visitor numbers — and queues at the entrance — tend to be highest. Spring and autumn offer milder weather outside and lighter crowds.

Who is it for?

The boat tour is calm and requires no particular physical fitness, making it a good fit for families with children and older visitors alike. It's also a strong choice for anyone interested in geology or history, offering a look at natural rock formations alongside traces of the region's oldest known settlement.

Frequently asked questions

Do I need to know how to swim to get on the boat? No — the boats are guided by staff, and passengers simply sit and take in the cave as they glide through.

How long does the visit take? The boat ride itself covers about 800 metres of navigable river; including the walk to the entrance and exit, the full visit usually takes 30 to 45 minutes.

Is it cold inside the cave? The temperature stays around 20°C throughout the year, so a light jacket or sweater is worth bringing regardless of the season outside.

Does the cave have historical significance? Yes — rock paintings and engravings over 17,000 years old, dating from the Magdalenian period, were found near the entrance, making the site an important archaeological location.