A river running 2,750 metres underground
La Vall d'Uixó is a town 15 km from Onda, in the direction of the coast. Below the Sant Josep nature area, at the northern edge of the municipality, flows an underground river with 2,750 metres of navigable passage: the longest in Europe accessible to the public. The water has been here for thousands of years, carving through limestone, forming galleries and creating a landscape that exists nowhere above ground.
Of those 2,750 metres, 800 are open to visitors. You explore them by boat, with a guide, as the cave is lit by spotlights that include underwater projections. The interior stays at 22 ºC throughout the year. The tour lasts around 45 minutes.
2,750 metres of navigable river underground. The longest in Europe with tourist access. The last gallery was discovered in January 2023.
What the visit is like
The entrance is at the Sant Josep Nature Area, a few minutes from La Vall d'Uixó town centre. Inside, small groups board boats with a guide and travel the underground river. Limestone walls, stalactites and the reflections of the illuminated water create an atmosphere unlike anything above ground.
The route passes through 14 distinct spaces: the Bat Room, the Oven Mouth, Diana's Lake, the Blue Lake, the Siphon Gallery, the Peñón Room, the Devil's Lake, the Dog Room, the Dry Gallery, The Medusa, the Flower Cascade and the Bethlehem Gate, among others. The lighting was designed by Carlos Buigas, the Catalan engineer who illuminated the Montjuïc fountains in Barcelona.
For those who want to go beyond the standard visit, there are two special options: Caving Kayak (€60, an active kayak journey through the river) and Origin (€100, a technical exploration of areas normally closed to the public). Both require advance booking and suitable physical fitness.
Arrive 10 minutes before your scheduled time. Tickets can be bought online or at the ticket office; no need to print them: showing them on your phone is fine.
Prices
| Ticket type | Price |
|---|---|
| Adults (over 17) | €18 |
| Children (3 to 12 years) | €12 |
| Under 3 years | Free |
| Reduced: over 65, students, youth card, disability, groups 20+ | €14 |
| Large/single-parent family: adults | €14 |
| Large/single-parent family: children 3–12 | €10 |
| Primary school groups (20+ pupils) | €8 |
| Secondary school groups (20+ pupils) | €10 |
| Caving Kayak experience | €60 |
| Origin experience (technical exploration) | €100 |
Reduced tickets require named proof of eligibility. No changes or refunds except in justified cases of force majeure. Prices 2025/2026: verify at covesdesantjosep.es.
History: 17,000 years underground
The area shows evidence of human occupation since the Upper Palaeolithic, around 17,000 years ago. Iberians and Romans also made use of the surrounding cavities. The cave entrance was even used as a shelter during the Spanish Civil War.
The first documented technical exploration dates to late 1897, when Valencian engineer José Gimeno Lassala became the first person to pass the initial natural siphon (the Oven Mouth) by boat, about 100 metres from the jetty. Until then, this obstacle had kept the interior inaccessible for thousands of years.
Interior lighting was installed for the first time in the 1950s. In 1960, 3,000 visitors came; the following year it was 20,000. Growth was so rapid that the definitive lighting was entrusted to Carlos Buigas, the engineer known as "the Wizard of Light". The Dry Gallery, which completes the current route, opened in 1969.
The most recent addition is very recent: in January 2023, the Alto Palancia Underground Expeditions Group discovered a new chamber, the Sala d'en Guillem, named after its discoverer. The cave keeps yielding surprises.
Video: Coves de Sant Josep.
How to visit Coves de Sant Josep from Onda
It's 15 km and about 25 minutes from Onda via the CV-20 towards the coast, turning off towards La Vall d'Uixó before reaching the sea. The cave is signposted from the entrance to the town.
Opening times vary by season. November to February: morning sessions only (10:00–14:00). March to October: afternoon sessions are added (15:30–18:00). Check exact times by calling 964 69 05 76 or on the official website, and book in advance at weekends and during high season.
The standard visit takes around 45 minutes. Combined with lunch in La Vall d'Uixó or Onda, it makes a comfortable half-day trip.
Where to eat
La Vall d'Uixó has bars and restaurants in the centre, with set lunch menus aimed at visitors. The Sant Josep nature area also has a picnic area outside for those who prefer to bring their own food. If you want more options, Onda is 15 km away.