Pahnloo Hot Spring

Pahnloo Hot Spring in the Ardabil Province of northwestern Iran is a sulfated, sodium, and bicarbonate-rich mineral spring in the volcanic highland landscape surrounding Mount Sabalan, one of Iran's most geothermally productive volcanic mountains whose extensive hydrothermal system feeds dozens of springs across the surrounding plateau and valleys. The complex mineral profile of Pahnloo's waters — combining sulfate, sodium, and bicarbonate in a single spring — reflects the chemical diversity of Sabalan's volcanic hydrothermal system, where different groundwater flow paths through the volcanic rock produce varied mineral compositions across a relatively small geographic area. The Ardabil highlands' landscape of alpine meadows, traditional Azerbaijani villages, and the Sabalan summit's year-round snow combine with the geothermal activity to create one of northwestern Iran's most compelling natural environments.