The diving cage sinks rumbling and swaying into the depths of the sea, water lashes against the portholes, it is narrow and dark, it is better not to be claustrophobic.

When the nautical instruments show a water pressure of four bars and a depth of thirty-seven meters, the elevator stops and a little panic sets in.

But it is unfounded, because in reality the box has not moved a single centimeter and the descent into the gorge of the Mediterranean Sea is only simulated using technical sophistication.

It's a spectacular prelude to exploring the replica Cosquer Grotto set in the futuristic, giant diving board-like Villa Méditerranée in the port of Marseille, which has recently welcomed visitors.

The entrance to the original Palaeolithic Cosquer Cave, with animal drawings, handprints and geometric hatching dating back thirty thousand years, is actually below sea level, in the Calanques massif of Marseille.

At that time, this "Louvre of the Stone Age" was still dry.

Only when the glaciers melted at the end of the last ice age was the cave flooded.

Today, three quarters of the cavern threatened with sinking are under water.

It was a coincidence that in 1985 the professional diver Henri Cosquer, who was now seventy-two years old and had a sturdy sea dog, was still active and diving, discovered the tubular entrance to the grotto and was able to penetrate to the caverns that had not yet been flooded and their art treasures.

For years, Cosquer kept quiet about his sensational find.

"It was my secret garden that I wanted to protect," says the namesake of the underwater site, which is unique in the world.

But when three amateur divers lost their lives while secretly exploring the cave in 1991, Cosquer decided to report his discovery to the authorities.

Today, the state watches over the sunken legacy of the first humans, has sealed the entrance with a heavy steel gate and only allows experienced underwater archaeologists to enter.

Penguins on the Mediterranean beach

We don't have to put on a diving helmet to inspect the replica of the grotto, but after the supposed dive into the sea we take a seat in a remote-controlled electric car that holds six people and is similar to that of ghost trains and pirate attractions in amusement parks.

The vehicle takes us silently into the bowels of the catacombs, whose cracked rock walls have been reshaped to the centimeter with synthetic resin.

The comments reach us through headphones.

We are amazed at how faithfully the skilled painters who reconstructed the famous prehistoric Chauvet Cave in the Ardèche have imitated the fine lines of the art-loving Homo sapiens using the same natural dyes as then: wood ash, plant substances and oxide pigments.

Between lustrous stalactite columns,

reflected in the pools of water, an amazing bestiary presents itself: horses with black manes, bison with fearsome horns, ibex in dense woolly fur and greasy seals.

The stars of this gallery are three penguins, a species rarely found in cave paintings.

The presence of these inhabitants of inhospitable icy deserts proves that polar conditions prevailed in Provence at the time the cave was formed.

After half an hour's drive we reach the end of the labyrinth of caves, but the journey through thousands of years of civilization and the history of the earth is not over yet.

A few floors up, the animals in the cave frescoes have been reproduced three-dimensionally in their original size.

A giant deer, almost the size of an elephant, poses with its mighty antlers, as big as an excavator shovel.

The saiga antelope stands out with its trunk-like nose and the aurochs with its massive body resting on short legs.

In this scientific exhibition you will also learn that the days of the original grotto are numbered.

Researchers fear that climate change and rising sea levels will completely submerge the primeval paintings by the end of this century.