Embalse de Lareo

The Embalse de Lareo lies in the municipality of Ataun, within the Aralar Natural Park, in the Goierri district of Gipuzkoa. The rockfill dam with a concrete face stands 40 metres high with a crest length of 364 metres. Its storage capacity is 2.4 cubic hectometres, modest compared to large Iberian reservoirs but sufficient to supply the municipality of Ataun and support the nearby Arriarán reservoir. Completed in 1988, the surroundings have since naturalised and now blend fully into the Aralar mountain landscape.

The main access starts at the Lizarrusti Pass, on the border between Gipuzkoa and Navarra, where the Aralar Natural Park Interpretation Centre is located. From there, the 7-kilometre return trail (roughly 2 hours 10 minutes) descends through the most extensive beech forest in Gipuzkoa to reach the reservoir shore. The route is rated medium difficulty, with 178 metres of accumulated elevation change and an initial stretch through a narrow gorge with vertical walls where metal chains serve as handrails. A tunnel carved through rock bypasses one of the canyon's obstacles before the path opens into the valley holding the reservoir. At the bottom, a 2-kilometre circuit loops around the water's perimeter.

The beech forests between Lizarrusti and Balankaleku cover roughly a quarter of the Aralar Natural Park's surface and form the most extensive beech woodland in the province. In autumn, the beech leaves shift from green through yellow and orange to a deep red over several weeks, drawing walkers and photographers. Beside the reservoir, the Labeo dolmen — a megalithic burial structure — records human presence in these valleys for millennia. Local legend links the reservoir to Basajaun, the mythical guardian of the Basque forests, and the Gipuzkoa Provincial Council has named it "Basajaun's bathtub" in its promotional materials.

The reservoir's surroundings are almost devoid of tourist infrastructure: no visitor centre, no cafes, no drinking water near the shore. This absence of facilities is part of the appeal — silence is broken only by water dripping over rocks, birdsong and beech branches creaking in the wind. Mount Sarastarri to the north offers a natural viewpoint over the reservoir for those extending the walk. Trail markers combine the red-and-white GR blazes with green park waypoints, and the path is well defined except in one or two descending sections where erosion demands careful footing. Dogs are permitted on a lead. The fresh mountain air and light filtering through the beech canopy create a landscape that shifts character with each season, from the green burst of May to the deep ochres of November.