This one is marked on the ign 1:25000 maps, and is to be found to the east of the lovely little town of St-Sauveur-le-Vicompte down a long trackway south through Crosville and Le Caneda into the Marais.
Unfortunately, it is not public footpath round here, and before I could get to the end of the trackway, there was a large, heavily chained and bolted gate preventing access.
Maybe another time.....
Something is not right. This message is just to keep things from messing up down the road