Doppelquelle – Grosser und Kleiner Heisser Stein
Alsace border area, Haut-Rhin, France
- Location
- Alsace border area, Haut-Rhin, France
- Water type
- sulfurous
- Temperature
- 38 °C
- pH
- 6.5
Water profile
Thermicity
Neutral
LowHigh
Soothing — neither hot nor cold, perfect balance.
Mineralisation
Bio-active
LowHigh
Rich in active gases or metals — a strong mineral character.
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
SoufreSulfuresSulfates
Doppelquelle – Grosser und Kleiner Heisser Stein is a sulphurous double spring nestled in a scenic natural setting, where two distinct hot mineral outlets emerge side by side from the earth. The warm sulphurous waters carry a characteristic mineral scent and have been valued locally within a long thermal tradition associated with well-being. This twin-source site offers bathers a raw, unspoiled encounter with geothermal energy in a quiet outdoor environment.
Insider tip — The Doppelquelle, or double spring, with its Grosser und Kleiner Heisser Stein outcrops, sits in the Upper Rhine plain near the Franco-Swiss border, where warm mineral water seeps through Tertiary sediments at around 38°C. The Germanic name reflects the long history of Alsatian-Swiss thermal culture in this border zone. The two warm stone formations visible in the stream have given generations of locals a discreet bathing spot amid Rhine valley meadows. The flat floodplain landscape, rich in migratory birds, makes it as much a nature stop as a thermal one.
Nearby
Frequently asked questions
How hot is the water?
The water is neutral here, around 38 °C — a perfect balance, neither too hot nor too cold.
What type of water is found here?
This spot features sulfurous water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année.