Access to this cave, over 30,000 years old, is via the original entrance to the seabed in the south of France, then by following a submerged trench of more than 100 meters which goes up and leads to a cave of 2,500 m2, largely submerged.

Arrived there, the still dry walls offer with regard to engravings and drawings of the Upper Paleolithic, in particular of marine animals, seals and penguins, unpublished on the great world sites of prehistoric archeology. An “aesthetic shock” that marks a life, says archaeologist Luc Vanrell, 62 years old, 30 of whom studied this site.

But today this cave is threatened with disappearance. After a sudden rise of 12 cm in sea level in 2011, the highest waters are rising a few millimeters each year.

For these French scientists, it is a race against time because this rise in water levels due to global warming associated with marine pollution undermines the masterpieces of parietal art from year to year.

To keep track of this unique heritage, the divers-archaeologists are intensifying their explorations, in particular to finalize a virtual representation of the cave, while a few kilometers away, in the heart of Marseille, technicians and artists are completing the construction of a replica intended to the general public, which will open on June 4.

On this spring day, the mission is to continue the 3D digital mapping of the walls of the cave, where some 600 “graphic entities” have already been listed. “Our fantasized objective would be to bring the cave to the surface”, smiles one of the divers, Bertrand Chazaly, responsible for digitization operations. “Finished, our virtual Cosquer cave, with millimeter precision, will be an indispensable research tool for curators and archaeologists who cannot physically access the site.”

– “Unique by its size” –

“At the time, we were in full glaciation, the sea level was 135 meters lower and the coast 10 km further”, says archaeologist Michel Olive, in charge of the study of the cave at the regional service. of Archeology (DRAC).

From the boat of the scientific mission, he draws with his finger a vast space now covered by the Mediterranean. “The entrance to the cave, slightly elevated and facing due south, faced a vast plain covered with grasses and protected by cliffs, an extremely favorable place for prehistoric man,” he says.

The decorated walls of the cave testify to the variety of animals present on the site: horses, ibexes, bovids, deer, bison and saiga antelopes, but also seals, penguins, fish as well as a feline and a bear… in total 229 figures of 13 species are represented.

Sixty-nine stencils of red or black hands and three involuntary handprints, including those of children, have also been listed, as well as several hundred geometric signs and eight male and female sexual representations.

A graphic richness due to the exceptional duration of the frequentation of the cave by men and women of Prehistory “between -33,000 years and -18,500 years before the present” according to the last dating, explains Luc Vanrell, present during this expedition.

“The density of the graphic representations places Cosquer at the level of the four largest caves in the world of Paleolithic parietal art with Altamira in Spain, Lascaux and Chauvet in France”, he estimates. “And since it is likely that the walls now under water were originally also ornate, this makes Cosquer a site unique in size in Europe.”

For this passionate archaeologist with a square face and a laughing eye, “it’s an addictive site”. “Some speakers who haven’t been down in the cave for a long time feel bad. They want their favorite bison,” he laughs.

He compares his dives to an “inner adventure”. “No one is bragging in this space cut off from the world, we are steeped in the environment,” he says.

– Discovered by chance –

It was in 1985 that Henri Cosquer, a professional diver and organizer of a diving school, said he had discovered by chance the underwater entrance to the cave, 15 meters from the shore.

In stages, he then dares to venture into the long trench going up 137 meters before emerging in a cavity dug by water and time in the limestone massif.

“One day, I surfaced in the cave plunged into darkness. You get soaked, you come out of the mud, you slip. It took me several forays to get around it. At first, I didn’t I saw nothing with my lamp and then I fell on the painting with one hand. It all started from there,” he told AFP.

While the law obliges to declare this type of discovery without delay for its preservation, man will reserve it for a long time, for himself and his relatives. “This cave belonged to no one. When you find a good mushroom spot, do you tell everyone you?”, He justified, cheekily.

But the rumor of an “underwater Lascaux” is circulating, attracting divers. Three will find death in the gut leading to the cavity. Marked by tragedy, Henri Cosquer, 72, made his discovery official with the authorities in 1991. The cave, authenticated as a major prehistoric site, would bear his name. But its entrance, secured by a gate, will now be reserved for scientific teams.

– “Irreversible damage” –

Over the next thirty years, dozens of archaeological missions were carried out to study and preserve the site, and to inventory its graphic riches. However, the means allocated suffer from competition from the Chauvet cave, discovered later, in 1994, but easier to access.

But, in the summer of 2011, Michel Olive and Luc Vanrell sounded the alarm after noting the sudden rise in water levels and irreversible damage to certain panels. “It was a disaster, a shock that broke us down psychologically,” recalls Luc Vanrell, referring to enormous damage to drawings of horses.

“All the data collected show that the rise in water is going faster and faster,” confirms geologist Stéphanie Touron, specialist in decorated caves at the Research Laboratory for Historical Monuments in France. “The sea, which rises and falls in the cavity according to climatic variations, washes away the walls and undermines information-rich soils,” she says.

The Cosquer cave also suffers the consequences of microplastic pollution which accelerates the degradation of paintings.

Faced with these threats, the French State, owner of the site classified as historical monuments in 1992, launched a national study to register this heritage as quickly as possible.

A new mission led by archaeologist Cyril Montoya, intended to better understand the activity of prehistoric men in the cave, should begin this summer.

– “Riddles to solve” –

Among the outstanding enigmas is the fortuitous imprint of a woven material on a wall, which could confirm the hypothesis of the making of clothing by hunter-gatherers at the time of the frequentation of the cave.

The representation of horses with long manes also raises questions. Luc Vanrell sketches the hypothesis of a first domestication or at least a penning of the animal by man because in the wild the manes are shorter, almost in brush, shaped by the vegetation at the mercy of the gallop horses. The drawing of lines evoking a form of harness reinforces this hypothesis.

“Archaeological soil preserved under a layer of calcite” (a mineral) must also be studied, explains Cyril Montoya, who mentions the presence of “remains of coal” used for painting or “heating areas on stalagmites” transformed into ” lampposts to illuminate the cave”.

The central question of the use of the cave remains unanswered, admits Michel Olive. If archaeologists agree that our distant ancestors did not live there, some speak of “a sanctuary, others of a meeting place, even of a site of extraction of mondmilch (also called milk of the moon, Editor’s note), this white matter of the walls used for body paintings or as a support for paintings and engravings”, he explains.

– “The replica bet” –

As soon as the cave was discovered, the idea of ​​creating a replica for a large public germinated.

But it will be necessary to wait until 2016 for the Provence-Alpes-Côte d’Azur Region to decide to set it up at the Mediterranean villa, an unused modern building located in the historic heart of the second city of France, next to the Mucem, the Museum civilizations of Europe and the Mediterranean.

For the company Klébert Rossillon, responsible for designing, building and managing the reconstruction – a project of 23 million euros, ten of which are financed by the region – the challenge was high: to fit the replica of the cave into a smaller space. while remaining as faithful as possible to the original. In the end, after a slight reduction in scale, “1,750 m2 of cavern, 100% of the painted walls and 90% of the engraved walls will be shown”, assures Laurent Delbos, in charge of the site.

To stick to the original, the company benefited from 3D modeling data from the cave collected by archaeologists under the aegis of the Ministry of Culture (Drac Paca). And she relied on a team of specialists in replicas of decorated caves with which she already built in 2015 a duplicate of the Chauvet cave, in Ardèche (south-eastern France).

“Prehistoric artists wrote (a) score a long time ago, I am one of their interpreters”, sums up the visual artist Gilles Tosello, 66, who has endeavored to reproduce prehistoric drawings as faithfully as possible, with the same tools and charcoal used at the time.

Sitting in the dark in his Toulouse studio facing a scale of a stucco cave lit by a projector, the artist told AFP his emotion by copying the detail of a horse: “What fascinates me in art prehistoric, it is the spontaneity of their gesture which is certainly based on great practice, great knowledge, great experience. This freedom of gesture, this sureness will never cease to amaze me until the end.”