DEEP BLUE EXPLORATION works for the discovery and study of mesophotic coral populations (between 50 and 150 meters) in Mayotte through participatory science actions.

The synergy created by the hard core of the association (created in 2019), combining naturalist photographers, scientists and popular science artists and authors, makes the most of each member for a single purpose: Explore - Study - Raise awareness and Contribute to the preservation of reef ecosystems.


The Twilight Zone


Deep Blue Exploration's action field!

Yet connected to surface reefs, the coral ecosystem of the so-called mesophotic twilight zone is an almost unknown space given its difficult access. In the tropics, it is approximately between 50 and 150 m deep. As the depth increases the pressure increases as the illumination of sunlight and the temperature of the water decrease. Far too deep for recreational divers, this dark and mysterious and potentially deadly space. It is imperative and vital to breathe complex and specific gas mixtures, largely composed of helium. It is then possible to access the zone less than 60 m deep for only a few tens of minutes, while the return to the surface will only be possible after several hours of decompression.


A descent to 120 meters in a few figures:


Panorama at 85 meters depth.



Deep Blue Exploration is the result of the joint effort of enthusiasts of the marine and underwater world. Motivated by a taste for exploration and discovery, the association puts all its energy into exploring, studying and preserving these environments and ecosystems, many aspects of which remain unknown to this day.

Gabriel Barathieu, président of DEEP BLUE EXPLORATION



Coral reefs are home to more than 25% of the global marine biodiversity, and traditionally have for the riparian populations (more than 500 million inhabitants in total), a considerable socio-economic importance. In addition, they protect coasts from erosion caused by waves and storm surges. Their lagoons are privileged waterways for indigenous populations, and their cultural and heritage importance are paramount.

Despite their essential role, coral reefs are currently highly threatened because of their increasing exposure to anthropogenic impacts directly linked to the inevitable increase in the world population, to the economic development of the countries concerned, and their openness to mass tourism. Impacts to which are added natural disturbances, and increasingly, the effects of climate change.





The scientific community has observed for many years an increase in the frequency, intensity and geographic extent of coral bleaching episodes. The increase in the population and the concentration of it near the coral reefs is the cause of a multitude of impacts (degradation, pollution, overfishing) strongly weakening these ecosystems. Impacts to which are added gradually but inexorably the effects of climate change.

With this sad reality, it becomes urgent to act rather than blaming it !!!


Beginning of an episode of coral bleaching.

From this perspective, coral reefs are to be considered as ecosystems of priority interest. Their heritage importance in the tropical regions of overseas France cannot therefore be underestimated. However, little is known about these coral ecosystems, particularly in the parts of the reef slopes that are deeper and more difficult to access (the "mesophotic" zone). Their preservation is both an effort to improve their knowledge through the use of innovative techniques and a wide targeted and effective dissemination of the knowledge acquired.

Professor Michel Pichon


Even today, an entire section of these coral ecosystems remains very poorly understood, particularly in the parts of the deepest and most difficult to access reef slopes (the "mesophotic" zone). Their preservation is part of an effort to improve their knowledge through the use of innovative techniques.


To better understand the roles and / or ecological functions of Mesophotic Coral Ecosystems (ECMs) for the coral biotope as a whole, a scientific approach is essential.


DBE's primary objective is therefore to help develop criteria to identify, by targeting the physico-chemical and biological factors that characterize them, areas of interest and / or particularly resistant / resilient to environmental changes.


Work 100 meters deep