Source du Doubs


diver John Volanthen - 2007



After 2 visits to this cave last year and several aborted trips in 2007 due to high water JV finally managed to arrange a trip during good conditions. The main difficulty with this cave is the water temperature which remains at 5 6 Celsius Year round. The current end of the cave was a boulder blockage encountered by JJ Bolanz at -55m, 250m into Sump2. The cave does not descend to -70m as described in the Cave diving guide to Eastern France.


JV installed a small habitat at -6m in S2. This was belayed to an Acro which was brought for this purpose and jammed across the rift at -7m. Various bailout cylinders were installed in S2. The diver had a lot of problems with demand valves freezing and free flowing as the temperature outside the cave was -6C and most seemed to contain small amounts of water which froze. As a result cylinders for the push the next day were ferried through S1 and stored underwater to prevent further freezing.


The diver made an uneventful trip through S1 and kitted up. Descending the Rift, the habitat was checked and one stage was deposited at the bottom of the shaft at -40m. The line is broken here deliberately by local divers to discourage further penetration. The continuation can be found on the floor at -45m by following the left wall down and proceeding 10m forwards. At this point, clear water is encountered, indicating that this major passage is not the main source of the slightly murkier water found in the shaft and resurging from the entrance. It is also possible to turn right at the bottom of the shaft, where breakdown is quickly encountered. This looks passable for a side mounted diver, but remains unexplored.

Continuing on the main line, a squeeze down through boulders is encountered within 50m (This is reported passable with back mounts by Andre Gloor) and 150m later 10 mins after leaving the shaft) the terminus of JJ Bolanz is reached. There are 3 possible ways on through boulders:

  • to the left a 3m long vertical slot ,
  • to the right a triangular shaped hole
  • and 3m back on the extreme right at the ceiling, a flat out squeeze above a boulder.

Having failed to pass the left hand slot before, the diver opted for the triangular hole and was able to pass by removing a cylinder. Beyond this blockage, open passage continued and the diver laid 150m of line in large 3x3m scalloped passage, turning only to limit decompression, mindful of the lack of surface support in the event of a problem. The diver was glad to reach the habitat and spend the 6m stop in relative comfort. All equipment including habitat was removed from the cave immediately after decompression was completed. Total dive time 2 hrs 40 mins. A return is planned with a scooter.


Informations complémentaires

Webcam location for the region:

Note: best conditions are less than 0.6m3 per second beyond this S1 becomes impassable


  • Castoro C96 CCR
  • 1x 12L Air
  • 1x 12L 10/50 TX
  • 1x 11L 35% at -40M
  • 1x 10L 58% at -15m
  • 1x 12L O2 at -6m

Habitat pitched at -6m using small Acro at -7M