Baume des Cretes is one of the several entrances to the great Vernau system
which is now a good 35 km long. A narrow 50 meter deep entry shaft has to be rappelled
Then: through a labyrinth of passages and shaft steps (so without further ropes is not possible)
The next obstacle is a fallen zone and the last one is a 15 meter abseil
in the collector. Once at the bottom you can walk a kilometer against the water flow and climb up until a large and beautiful hall comes. Down the river the passage ends after a few meters with an siphon.