Plenty of warm water enters the river Sals in this old town. But is it worth coming here in the winter? I went to check out 3 possible bathing spots.
On the riverside below the road, just outside the town is this pool. You can get there if you park next to the Les Thermes de Rennes les Bains, walk down to the river, cross it, walk a bit further away from the town and cross again. Water comes from the old roman bath “La source des bains doux”. Probably the nicest free pool in town, but due to freezing temperatures was not tempted to cross the river to find out the exact water temperature. My guess would be 30ºC-ish.
There is also a discharge of 33°C warm water from the spa strait into the Sals. While we were visiting the little stone pool was flooded by river water.
We found that the gate to enter Bains Forts from Rue des Bains Forts where closed. Alternatively we went down the steps from the Pont de Montferrand to reach the riverside. From there you still need to wade across the river. The original pool is still there, but barely holds any water. The thermal water now ends up in a small pool adjoined to the river partially covered by a concrete slab. So if you want to have a reasonable hot bath (35ºC-ish) in Renne les Bains you have to squat inside this hole. I assume the river water, which definitely enters the pool, is not the cleanest as it has the distinct smell of detergent to it.
Rennes-les-Bains, Occitania, France: The coldest days of the year are not ideal time to bathe here, since the only hot option is quite crowded and not exactly hygienic. I can imagine having a better time in summer when he other sources become warm enough to enjoy. – bert