Arnost Ceral by David Blazek.
We were guided here by Bastien Marlin during a Horsefeathers trip to France. Funniest thing with this ditch in Montpellier was that the walls were so steep and tall that we couldn't even get into it. Eventually, we found one place where we slid down- not really thinking how we were going to get back out. Running through the bottom of the cavern was a stream which ate Arnost's board a couple of times before he landed this huge frontside flip to fakie. Can't remember what other tricks went down, but this one was definitely the hammer!