Prérouge Grotto in Arith is in the Bauges (73), if departing from Annecy, drive through Alby/Chéran, Cusy or Allèves then follow the sign to Lescheraines. Turn right and follow the touristic sign “Grotte de Prérouge” taking you to the parking.
Then, walk on the bridge over Chéran river to see the grotto, mill and the lovely Chéran river side.
Only a small part of the Grotto can be seen by us, after it is a 55 km long network only to be seen by speleologists.
The entrance of Prérouge Grotto is the access to this 55km underground network, it is under the Bange mountain, Prépoulain woods and the Revard mountain.
If you visit it in the summer, you can go into the Grotto a little bit (be careful as slipery), also the entrance of the Grotto can be impresssing due to heavy rains (but of course do not go in if raining)
For a lovely walk between the fields, river and forest (1h), walk 300m from Bourg de Lescheraines – the bridge, heading to Arith (D62b). Turn right after Arith Bridge (mill), follow the path to the Prérouge mill.
Lovely chocolate and ice cream shop before reaching Lescheraines, also to be seen in the area: the Lescheraines ponds, Pissieux waterfall, Tour St Jacques…
You could also drive back to Annecy going through Col Leschaux and finish by Annecy lake in St Jorioz.
https://www.lesbauges.com/grotte-de-prerouge.html