Sources Chaudes de Mérens-les-Vals

A short climb of around twenty minutes above the village of Mérens-les-Vals, on the GR10 long-distance trail through the Ariège Pyrenees, leads to a set of natural rock basins where sulphurous water gathers at roughly 30°C. Unlike the formal thermal establishments seven kilometres away in Ax-les-Thermes, this spring has never been captured in concrete or piped into a commercial facility — the water simply pools where it emerges from the mountainside, in three linked hollows carved by the flow over time. Mérens-les-Vals, better known for the sturdy black mountain horse breed that carries its name and for a modern mineral-water bottling plant opened in 2020, remains a quiet base for hikers seeking an unmanaged soak with views over the upper Ariège valley.