Fuente de los Baños de Montanejos

Fuente de los Baños de Montanejos is a natural thermal spring in the town of Montanejos, in the Alto Mijares region of Castellón province, and one of the defining natural attractions of this part of Spain.

What makes the water in Montanejos warm?

The spring emerges from the limestone bedrock of the Mijares river valley at a constant temperature of around 25°C, unaffected by the season. Its flow rate is estimated at roughly 6,000 liters per minute, enough to continuously feed a natural pool and a stretch of the adjoining riverbed. The water carries a sulfate-magnesium bicarbonate composition with mineralization around 700 mg/l, placing it in the oligomineral, medium-mineralization category.

Why can you swim here all year round?

The answer lies in how the warm spring water meets the cold current of the Mijares. Natural rock barriers and weirs keep the thermal outflow separate from the river's cold water for close to a kilometer before the two finally merge. This creates a distinct "thermal stretch" of riverbed where the water stays pleasantly warm even in winter, an unusual feature among natural bathing spots in Europe.

What is the history behind this site?

The healing properties of the water were already being sought out in the eighteenth century, when locals and visitors used it for its high sulfur and magnesium content. Its significance was formally recognized in the nineteenth century, when a Royal Order dated 13 October 1863 declared the mineral-medicinal waters a matter of public utility. On the right bank of the Mijares, the remains of a bathhouse of Arab origin, dating to the twelfth century, are still visible today. Local tradition links its construction to Zayd Abu Zayd, the last Almohad ruler of Valencia, said to have ordered the baths built for the women of his harem and for his own use. In 1997, a modern spa, the Balneario de Montanejos, opened in the town, extending the site's therapeutic and wellness tradition into the present day.

What should visitors know before coming?

The Fuente de los Baños sits right next to the center of Montanejos, framed by the limestone cliffs of the Mijares valley, making it easy to reach for both day-trippers and travelers staying longer in the region. The natural pool and the warm stretch of river are popular in summer for the refreshing contrast with the surrounding heat, and in winter precisely because the spring's constant warmth turns it into one of the few natural bathing spots usable outside the summer season.

Frequently asked questions

What is the water temperature at Fuente de los Baños? The spring maintains a constant temperature of around 25°C throughout the year, regardless of the season or air temperature.

Can you swim there in winter? Yes. Because the spring stays at a steady temperature and is naturally kept apart from the cold Mijares water, bathing is possible year-round, and the contrast is most noticeable during the colder months.

Where does the site's history come from? The name refers to old baths whose Arab-era remains, dating to the twelfth century, still stand on the river's right bank. Local tradition attributes their construction to Zayd Abu Zayd, the last Almohad ruler of Valencia.

Does the water have therapeutic properties? Yes. Its sulfate-magnesium bicarbonate composition has been used for therapeutic purposes since at least the eighteenth century, and the waters were officially declared of public utility in 1863.