Cosquer Cave, art drowned beneath the Mediterranean

In the calanques of Marseille there is a cave that can only be reached by diving thirty-seven metres below the surface of the Mediterranean, following a flooded passage 140 metres long, before surfacing into a chamber where the air is still breathable and the walls have been covered, for twenty-seven thousand years, with horses, bison, auks and hand stencils. The cave is called Cosquer, after the diver who found it. It is unique in the world: the only known decorated cave whose entrance lies under the sea¹.

Its discovery owed everything to exceptional coincidence. In 1985, Henri Cosquer, a professional diving instructor based in Cassis, was exploring the submarine walls of Cap Morgiou in the calanques east of Marseille. At 37 metres depth, he spotted a tunnel opening in the limestone. He swam up through it, discovered an immense chamber, and did not immediately grasp what he saw on the walls. Only in 1991, on a second exploration with colleagues, did he notice hand stencils, those hand silhouettes made by blowing pigment around a hand pressed flat against the rock. He alerted the authorities. The cave's parietal art was officially recognised in 1991¹.

Why is the entrance underwater?

The answer lies in the planet's climatic history. Twenty-seven thousand years ago, when the first artists entered Cosquer Cave, we were at or approaching the Last Glacial MaximumLast Glacial MaximumThe peak of the last glaciation (c. 26,000 to 19,000 years ago), with ice sheets at their greatest extent; it pushed populations towards southern refuges.→PleistoceneThe geological epoch of the great ice ages (c. 2.6 Ma–11,700 BP), spanning most of human prehistoryPrehistoryThe span of human history before the invention of writing, from the Palaeolithic to the Metal Ages, known mainly through material remains.→.→. Mediterranean sea level was then some 120–130 metres lower than today: a colossal volume of water was locked in continental ice sheets in North America, Scandinavia and the Alps. The Marseille calanques did not yet exist in their current form, they corresponded to river valleys carved well inland from the shoreline.

Cosquer Cave's entrance was therefore, at the time of the earliest paintings, about 80 metres above the sea level of the period, reachable on foot, from a cliff or coastal slope now vanished beneath the waves. Only gradually, as glaciers melted and the sea rose (roughly between 20,000 and 6,000 years ago), was the entrance drowned. The inner chamber was never flooded, because it sits high enough in the karstKarstA limestone landscape shaped by rock dissolution, rich in caves and passages; its sediments can preserve bone and DNA over long timespans.→ to have always retained an air pocket, and that air pocket is what preserved the paintings².

Art of two phases

Research since the discovery has identified two major artistic phases, separated by several millennia. The first, dated to around 27,000 years ago (GravettianGravettianAn Upper Palaeolithic culture (c. 33,000–21,000 BC) spanning from the Atlantic to Siberia, famous for its ivory female figurines ("Venuses") and, at Dolní Věstonice, the oldest fired ceramics.→), is characterised by hand stencils and geometric forms: signs, dots, abstract marks. The hands are the most numerous, over sixty-five, and their presence gives this first phase an intimate, ritual character, as if the artists sought to leave a direct trace of their bodily presence on the rock.

The second phase, dated to around 19,000 years ago (SolutreanSolutreanA European Upper Palaeolithic culture (c. 22,000–17,000 BC), remarkable for its leaf-shaped lithic points worked with flat retouch. Contemporary with the second art phase of Cosquer Cave.→ or Epigravetian), is more animal-focused. It yields an exceptional bestiary: horses, bison, megaloceros, ibex, but also species rare in PalaeolithicPalaeolithicThe oldest and longest period of prehistory (c. 3.3 Ma–12,000 BC), defined by chipped stone tools and a hunter-gatherer way of life.→ art, giant auks (Pinguinus impennis, the now-extinct great auk), seals, and a jellyfish. These marine representations reflect a familiarity with the coastline and coastal fauna that mirrors the sea's proximity at the time¹.

In total, the cave holds more than 517 parietal figures, including 177 animals belonging to at least eleven different species. This density and diversity make it one of the most important cave artCave (parietal) artArt made on the walls of caves and shelters (paintings, engravings), as opposed to portable artPortable artTransportable art objects (figurines, engravings on bone or ivory), such as the Palaeolithic Venuses.→.→ sites of Mediterranean prehistory.

The tragedy of the divers

Cosquer Cave is beautiful, but dangerous. Its underwater access means only experienced divers can reach it, and even for them, the passage is formidable: 140 metres of flooded tunnel, at 37 metres depth, in cold water with limited visibility. Between 1991 and 1994, before access was officially closed and secured, three divers lost their lives attempting to reach the cave. They became lost in the tunnel on the way back, trapped between the submerged entrance and the painted chamber. Their bodies were recovered inside the cavity. Since then, access has been strictly regulated and reserved for authorised researchers².

The threat of rising seas

Cosquer Cave is threatened, not only by reckless divers, but by the foreseeable rise in sea level caused by climateClimateThe long-term average atmospheric conditions of a region; its variations (glaciations, aridifications) shaped migrations, agriculture and the collapse of prehistoric societies.→ change. At present, the main chamber sits about two metres above the internal sea level. If Mediterranean levels rise by several decimetres to a few metres over the coming centuries, as projected by the worst-case IPCC scenarios, water will eventually invade the cavity. The paintings, until now preserved in a stable, isolated atmosphere, would be exposed to humidity, temperature fluctuations and marine algae. Deterioration could be rapid.

Faced with this threat, an intensive documentation campaign has been under way since the 1990s: photogrammetric surveys, 3D modelling, line-by-line recording of every figure. These archives now constitute a complete digital replica of the cave, which will survive even if the artworks themselves are eventually destroyed³.

The Marseille replica

In June 2022, a full-scale replica of Cosquer Cave opened to the public on the J4 esplanade of Marseille's Vieux-Port, in the Villa Méditerranée adjoining the MuCEM. This "Cosquer Méditerranée" is a technical and artistic tour de force: sculptors, painters and speleologists reproduced the cave with remarkable fidelity, recreating the karst, the concretions, and every painted or engraved figure. The visit is on foot, without diving, allowing the public to discover the cave's art in optimal safety and comfort.

This replica is not simply a museum. Like the Lascaux IV or Chauvet-Pont d'Arc facsimiles, it is a work in its own right: a way of democratising access to a heritage that nature (the sea) and conservation (pigment fragility) make physically inaccessible to the vast majority of humanity³.

Cosquer and the geography of the Palaeolithic Mediterranean

Cosquer Cave illuminates the prehistory of the western Mediterranean with a particular light. It proves that, twenty-seven thousand years ago, the shores of this sea were home to human groups capable of creating elaborate art, and that this art has almost entirely vanished beneath the waves since deglaciation. How many other decorated caves, other coastal sites, other hunting or fishing camps were submerged between 20,000 and 6,000 years ago, as the sea invaded the coastal plains of the Mediterranean? Cosquer Cave may be the sole survivor of a submerged archaeological heritage of an amplitude we can only imagine.

It also invites reflection on what we call the "Mediterranean". This sea, today fringed with beaches and resorts, was, in the Palaeolithic, something radically different: a smaller, more confined space, with shorelines tens of kilometres from where they are today, and human populations who had no sea to cross to reach what is now under water. Cosquer Cave, with its painted auks and seals, speaks of that lost world, a world where the calanques did not yet exist, where the Mediterranean was smaller, and where Solutrean men and women pressed their hands against the darkness of a cave to leave, for ever, their mark.