La Mescla: A Sump Dive in France

I was ecstatic as I punched “send” and officially bought my airline tickets to the French Riviera. My heart pulsed wildly at the idea of diving the cave system ‘La Mescla’, one of the last completely unexplored systems in the area around Nice. The cave begins and continues deep into the mountainside of the French Alps. Few divers have access to this gem because of the location and difficult access. Although it does have a long history of exploration that goes back to 1897 the end of the cave has yet to be found.

La Mescla is one of the more interesting caves in the region because the carved limestone has been vertically rotated. The ground has literally twisted like a corkscrew over time. This enabled concretions and formations that were once above the water line to now exist under the water so there are beautiful decorations throughout the cave.

Right: Geoffrey May inside La Mescla cave.

Cave diving in France is very different from cave diving in Florida; it wasn’t just a case of backing up the SUV to the spring, doing a short walk and then popping in. The cave was a sump dive, that is, there were times during the dive when we would surface and walk until the next water filled passage. The dry sections of the cave offered many challenges. We had to negotiate a series of ladders, steep inclines, squeezes, and even a so called footbridge that was nothing more than a four inch wide piece of metal - all the while balancing a set of double tanks. No mean feat given the cave was damp and slippery and the path was coated by a layer of clay and mud.

Yet Frederick Banacossa, my dive buddy and guide, considered this an ‘easy’ dive, as we didn’t need to set up any specialized climbing gear ourselves. The group who was ‘pushing’ the system and regularly carried a multitude of cylinders and DPVs into the cave had left several ladders behind at key junctions and also installed some homemade handholds from bent rebar directly into the rock. This meant we could leave the ropes, carabineers, and harnesses at home.

The weight of my equipment become ever more noticeable as we negotiated the dry sections of the cave and I had never before been so eager to sink into 65 degree water without a drysuit on. Being a thin-blooded boy from Florida, that is considered “cold” water for me, especially in a 5mm wetsuit. The cool, clear water was instantly invigorating both physically and mentally and I was ready for the dive.

We descended into the gin clear water and the underwater underworld of France came into view for the first time. The cave was amazing. To appreciate every moment, I swam slowly and peered carefully into every nook and cranny. Soon we made the gradual ascent and neared the first dry section. Breaking the surface I poked my head up to see a room that could only be compared to fantasy cave scenes I had seen in Hollywood movies. Marvelous rock layers with spots of stalactites in certain areas and countless earth tones of color surrounded me.

Geoffrey May negotiating the 'foot bridge' inside La Mescla cave.

The next sump had a visibility-altering halocline, an area where the fresh water coming from the top of the mountain was floating upon our warmer and lightly salted water. This feature of the dive is referenced in the local name for the system, La Mescla, meaning “mixed,” referring to the mixture of fresh and salt water.

Swimming onward we saw a large mound of khaki colored clay in the middle of the cave. It seemed innocent enough but further inspection revealed a plethora of tiny bones littered throughout. This was a “bat cemetery” that had been in the cave for hundreds or even thousands of years. Generation after generation of bats had left layer upon layer of these bones for us to see.

Soon after rounding another bend in the rock, our depth neared 120 feet (40 meters) and I could start to see a deep dark chimney that loomed in front of me. The line came to a tie off then darted straight down into the depths that would be unobtainable to us on this dive. Our bright HID lights shined nearly to the bottom, which was clearly another 60 feet (20 meters) down. To venture there would have required a completely different dive plan and substantially more equipment than we had, so after a moment of looking around we began the slow swim back.

Soon the dive was over. I surfaced with a large smile and could hardly stop gushing about our adventure. Although climbing out should have been more difficult than climbing in, the the additional energy from the dive made the hike out a “walk in the park.” I was exhilarated to have had a chance to experience something that very few people would ever have the opportunity to see.