Documentary: “Cap Corse, the mystery of the rings” on Arte, scientific investigation in the Mediterranean

In 2011, during an oceanographic campaign in the Cap Corse and Agriate Marine Natural Park, two researchers from the University of Corsica made a surprising discovery: hundreds of circles 20 meters in diameter appeared on their sonar screen. At a depth of around 100 meters, these shapes, with their almost identical structure, created a curiously ordered, almost artificial landscape. "A bit like a French garden," marveled Laurent Ballesta, during his first dive at the site. How can such a phenomenon be explained?
The biologist, photographer and diver, author of several documentaries (including Planète Méditerranée , available on arte.tv ), loves challenges: he sets out to solve the enigma with the collaboration of around thirty scientists (geologist, paleoclimatologist, algae specialist, etc.). His film follows this collaborative investigation step by step, from the first maps and ultrasounds of the subsoil using an autonomous drone to an ambitious underwater expedition organized with the French Navy.
For about twenty days, Laurent Ballesta and three other experienced divers confined themselves in a pressurized capsule to explore the site, collect samples, and inventory the ecosystem present there. Part sporting feat, part high-tech adventure, this scientific investigation gradually transforms into a journey through time, with these strange rock and coral formations dating back to the last glacial maximum, nearly 21,000 years ago.
As educational as it is contemplative, the film reveals the incredible biodiversity of the abyss: dogtooth groupers (a species that has almost disappeared from the Mediterranean), star rays, forests of gorgonians, fluorescent yellow snails and camouflaged shells... So many strange beauties that Laurent Ballesta's superb shots make us want, more than ever, to protect them from the threat of global warming.
La Croıx