Fugro Digital and 3D Expert Bertrand Chazaly started digitising Cosquer Cave in 2010. With its precious prehistoric paintings and engravings being engulfed by rising sea levels, Bertrand describes his urgent mission to capture the cave, access tunnel and entrance in three highly accurate, georeferenced 3D models.

Cosquer Cave is the most fascinating and rewarding project I’ve ever worked on. It is located in the Urgonian limestone at Cap Morgiou, near Marseille, France, and was first discovered in 1985 by experienced French diver Henri Cosquer. 

The entrance is hidden in the rock face, 37 m below sea level. Accessing the cave is not for the faint-hearted: divers must first swim up a steep, narrow, 120 m tunnel in complete darkness.

The cave’s existence was a closely guarded secret until 1991, when three divers became disorientated in the tunnel and tragically lost their lives.

Prehistoric artwork

The third of the cave above sea level is a treasure trove of 177 perfectly preserved prehistoric paintings and engravings. Created between 27,000 BC and 18,500 BC, they include horses, bison, penguins, seals, hands and phallic symbols. Sadly, all the artwork below the waterline has disappeared.

Given the cave’s cultural significance, in 2010 the French Ministry of Culture commissioned Fugro to digitise the above-water cave structure, paintings and engravings. Between September 2010 and December 2017, I completed more than 70 dives in the cave to create a georeferenced 3D model.

With sea levels rising and many of the painted figures getting perilously close to the waterline, in 2021 the Ministry recommissioned Fugro for a final scanning project involving around 45 more dives. 

Fugro’s bespoke 3D scanning technology will create 3D models, videos and highly accurate maps of the cave

Luc Vanrell, professional diver, in charge of scientific missions in the Cosquer Cave for the French Ministry of Culture, commented,
"To achieve the objectives of a 3D digitisation fully exploitable for our scientific team, we had to find a provider who could mobilise and develop multiscale 3D survey technologies, above and below water, and in extreme conditions. Fugro is the perfect partner to support us in this crucial mission."

The challenges

People don’t realise how long it takes to scan the cave or how exhausting it can be. The challenges include:

• Diving at 37 m below sea level
• Having to use a special ‘froglike’ swimming technique in the access tunnel to avoid disturbing the sediment
• Carrying and using equipment (batteries, computers, scanners, cameras and lighting) underwater and in watertight casings
• Never touching the cave walls, to avoid damaging the precious artwork or changing the shape of the walls (some are made of soft clay)

Section view of the Cosquer cave showing the steep, narrow, 120 m access tunnel

The 2021 survey

The latest project started in May 2021 and should finish in early 2022. We will use Fugro’s bespoke 3D scanning technology to capture the above-water and underwater sections of the cave, the access tunnel and the landscape around the entrance. Each figure will be photographed in detail and have its own precise coordinates, and we will create a high-density textured 3D model of all painted and engraved panels.

Horse 3D panel

Our Geo-data will be also used to create a replica of the cave and an exhibition at Marseille’s Villa Méditerranée, which is expected to attract around 500,000 visitors from around the world every year. European culture channel ARTE are also making a TV documentary about the project.

DID YOU KNOW?

- 20,000 years ago the sea level was between 120 m and 150 m lower than it is today

KeyFacts Energy Industry Directory: Fugro