The Coves de Sant Josep are home to the longest navigable subway river in Europe, with a total length of 2,750 meters, of which 800 meters constitute the tourist route. They are located in the municipality of La Vall d'Uixó, at the entrance of the Sierra de Espadán Natural Park. The tour is done by boat through galleries and lakes where water has shaped the rocks for thousands of years, and where mankind found refuge during prehistoric times. Declared a Historic-Artistic Monument in 2000.