A deep pool in the middle of the forest
Fuentes de Ayódar is a small village wedged between ravines and pine forests, with more springs than streets. A few minutes upstream, following the course of the Río Chico, you reach Pozo Negro: a deep pool of dark-green water surrounded by reddish sandstone walls and dense vegetation. The combination of the red rock characteristic of Sierra de Espadán Natural Park and the clear water produces a contrast you would not expect so close to Onda.
The name is no accident. In the centre of the pool the depth reaches around three metres, enough to lose your footing and to make the water look almost black when direct sunlight does not reach it. A small waterfall feeds the pool constantly from one side, while the river continues between rocks and smaller pools further upstream and downstream.
The trail along the Río Chico
Getting to Pozo Negro is part of what makes the place special. The trail starts in Fuentes de Ayódar and follows a track and well-marked paths along the Río Chico, with shaded stretches under poplar, pine and alder trees and more open riverbank sections. The total distance is around 5 km (there and back), with less than 100 m of elevation gain and low difficulty: a family-friendly outing if you wear appropriate footwear and take your time.
Along the way you pass small pools, vegetable gardens and springs that explain why the village is called "Fuentes" (Springs). The route coincides in part with the long-distance trail GR-333, which circles the entire Sierra de Espadán. The final section before the pool runs enclosed between rock walls, with the sound of water echoing between the stones. Then the path opens up and the pool appears, almost flush with the rock.
You need to scramble a short slope at the end to see the pool from above. It is not difficult, but wet rock is slippery: wear shoes with grip. If you plan to swim, water shoes are very useful for getting in without slipping on the rocky edges.
A postcard swim (with rules)
In summer Pozo Negro becomes one of the most popular natural swimming holes in inland Castellón. To protect the environment and prevent overcrowding, the local council manages access during the high season: maximum capacity of 70 people, a fee of 3 euros per person per day (free for children under 10) paid at the car park, and environmental wardens on duty. Check the council website before visiting to confirm current dates and conditions.
The water is cold even in August, which is part of the appeal. This is not a pool where you laze for hours, but an invigorating plunge into a deep rock basin. The surroundings are fragile and at risk of forest fire, so the rules are mandatory:
- No jumping from the rocky walls
- No fires
- No littering
- Follow the safety signage
- No conventional sunscreen in the water (use mineral sunscreen if necessary)
Beyond the pool
Although Pozo Negro is the best-known image of the area, Fuentes de Ayódar has more to offer. In the village itself there are several historic springs, old wash houses, and a curious structure called el Cubo, an ancient rectangular winery where grapes were trodden in medieval times. There is also a small water museum in the old mill and an ethnographic display on the threshing floors.
Upstream and downstream of Pozo Negro there are other less-visited pools: Pozo del Perejil, near the Fuente del Cañar, and Pozo de la Cantarera, the closest to the village. Either makes a good alternative on busy days when the main pool reaches capacity.
The Río Chico route can be extended or combined with other marked trails in the Espadán-Mijares area. On weekdays in spring or autumn, when almost nobody is around, the place bears little resemblance to the Pozo Negro that circulates on social media.
How to visit Pozo Negro from Onda
From Onda the drive takes about 40 minutes along secondary roads that climb towards the Sierra de Espadán, winding through ravines and pine forests. There is no useful public transport: a car is essential. The most convenient option is to park at the dedicated car park at the edge of the village and start walking from there. In summer, arrive early to secure a parking space and to enjoy shade for most of the trail.
Allow at least half a day to go at a relaxed pace: trail, pool and back to the village. If you want to combine the trip with something else, the Espadán-Mijares area has other villages and beauty spots nearby, and Onda works perfectly as a base for an overnight stay.
Where to eat in Fuentes de Ayódar
The village is small and so is the dining offer: a couple of village bar-restaurants aimed at hikers and day visitors, serving breakfast, simple set menus and home-cooked dishes. For more variety, head back towards Onda or stop at one of the nearby villages in the Espadán-Mijares area, where most places have at least one or two bars serving traditional inland cooking.