De l’eau sous la montagne, a film following French cave diver Frédéric Swierczynski’s most recent challenge – to find out how deep the forbidding underwater cave at Mescla really is – won the Grand Prix du film dáventure at the International Festival of adventure films in La Rochelle in November 2016.
An underwater cave so massive that not even ‘extreme’ divers can get to the bottom of it is keeping its deepet secret to itself – for now.
Frédéric Swierczynski broke a world diving record last summer for his 267-metre descent into the cave at Mescla, beneath the commune of Malaussène, 40km from Nice.
However, he did not reach the bottom of the cave, and still no-one knows how deep it is.
In October, another diving team went down into the cave to retrieve the decompression chamber Mr Swierczynski had left behind, but they stopped at 180 metres.
“I will try again to reach the bottom, but I don’t know when!” Mr Swierczynski, 43, told Connexion. “This kind of dive pushes the physiological limits of the body, due to the pressure. But it is also exciting, as it is virgin territory.
“No-one even knows for sure where the deepest waters in the cave have come from. Some evidently filters through the cracks in the limestone of Mont Vial, in the valley of the Var, but mystery surrounds the heated, salt water that bubbles up from the depths of the cave. It is thought to have come from the old riverbed in the Var, when the Mediterranean Sea was 1,000 metres lower,” said Mr Swierczynski, referring to tectonic plate movements that pushed up the Alps and raised the sea level millions of years ago.
His record-breaking dive took seven hours, with two of those spent in the decompression chamber. The equipment used for the dive had to be modified to withstand the pressure, and is extremely heavy: Mr Swierczynski and the divers who accompanied him were each carrying 200kg on their backs. That was why they had left the decompression chamber behind, he explained.
He added: “It’s beautiful and peaceful down there, and my phone doesn’t ring! It’s the only time in my life when my brain is fully concentrated on one thing, which makes it restful.”
The specialist equipment used in cave-diving, including rebreathers and driver propulsion vehicles or ‘scooters’, as well as the advanced technical skills required, mean there are few practitioners of this ‘extreme sport’ in Europe and around the world.
It is also one of the most dangerous forms of diving, due to the risk of decompression sickness and drowning. Unlike free surface-diving, in an emergency the diver cannot swim vertically to the surface: due to the ceilings of the cave, she or he must swim all the way back out.
A cross between spéléologues (cave experts) and divers, these intrepid underwater explorers are nicknamed spéléonautes. In Europe, only three will go deeper than 250 metres, and Mr Swierczynski is the only one to descend as deep in the cave at Mescla.
However, despite the extreme challenge of exploring this cave, he was not afraid of the dive.
“It was a continuation of my current depth training, and the logical next step in my experience of cave-diving,” he said.
Only licensed cave divers are allowed to go down into the cave at Mescla, which requires three consecutive dives for each of its three levels.
Mr Swierczynski started out with sea-diving when he was seven years old, in the Bassin d’Arcachon near where he grew up. He got into cave-diving at 18, and two years later he did his longest-ever dive in the Font del Truffe in Lot: it lasted 27 hours. He has never had an accident, he said, only unavoidable ‘incidents’. Yet accidents do happen, and there are plaques at Mescla in memory of divers who have drowned there.
Although most cave-divers who get into accidents are untrained, even experts can face serious difficulties due to the unstable nature of the territory. For example, a previously unexplored pocket of a cave that has been drained by an underground river could collapse on a diver, or a storm could transform a calm underground lake into a dangerous whirlpool. Even a small hand movement could throw up clay and create a cloud of fog that completely disorientates the diver, while if there is an equipment failure, he or she must remain calm to take the correct, life-saving action.
Despite these challenges, divers persist in their exploration of the cave at Mescla – as well as others in France and elsewhere – determined to uncover the mysteries of the deep.Although currently unfathomably deep, Mescla is not thought to be the deepest underwater cave in the world. That honour belongs to a cave in Hranice in the Czech Republic. In September, Polish cave diver Krzysztof Starnawski dived 200 metres, before deploying a remote-controlled underwater robot to reach a further 204 metres – but it did not hit the bottom of the abyss.