The source of the Doubs

Springing from a 55-meter-deep siphon, the waters exit a deep cavity which has only been partially explored up until now. Galleries are fed by the water falling onto the Risol massif and infiltrating into the limestone cracks. The temperature of the water on exiting the cavity is never more than 6 degrees. From its source to the Saone into which it runs, the Doubs travels a distance of 458 km, when both points are only separated by 90 km as the crow flies!