Rare coral reef discovered near Tahiti by UNESCO mission

A scientific research mission supported by UNESCO has discovered one of the largest coral reefs in the world off the coast of Tahiti. The pristine condition of, and extensive area covered by, the rose-shaped corals make this a highly valuable discovery.

To date, we know the surface of the moon better than the deep ocean. Only 20% of the entire seabed has been mapped. This remarkable discovery in Tahiti demonstrates the incredible work of scientists who, with the support of UNESCO, further the extent of our knowledge about what lies beneath.

Audrey Azoulay, UNESCO Director-General

Highly unusual discovery

The reef is located at depths of between 30 and 65 metres. It is approximately 3km in length and between 30m and 60/65m wide, which makes it one of the most extensive healthy coral reefs on record. The giant rose-shaped corals are up to 2 metres in diameter.

This is highly unusual because, up to now, the vast majority of the world’s known coral reefs sit at depths of up to 25m. So this discovery suggests that there are many more large reefs out there, at depths of more than 30 metres, in what is known as the ocean’s ‘twilight zone’, which we simply do not know about.

It was magical to witness giant, beautiful rose corals which stretch for as far as the eye can see. It was like a work of art.

Alexis Rosenfeld, French photographer and founder of the 1 Ocean campaign

A step forward for science

This expedition is part of UNESCO’s global approach to mapping the ocean. Coral reefs are an important food source for other organisms so locating them can aid research around biodiversity. The organisms that live on reefs can be important for medicinal research and reefs can also provide protection from coastal erosion and even tsunamis.

French Polynesia suffered a significant bleaching event back in 2019 however this reef does not appear to have been significantly affected. The discovery of this reef in such a pristine condition is good news and can inspire future conservation. We think that deeper reefs may be better protected from global warming.

Dr. Laetitia Hedouin, France’s National Centre of Scientific Research (CNRS)

Until now very few scientists have been able to locate, investigate and study coral reefs at depths of more than 30m. However, technology now means longer dives at these depths are possible. In total the team carried out dives totalling around 200 hours to study the reef and were able to witness the coral spawning. Further dives are planned in the coming months to continue investigations around the reef.

Unesco’s action for the ocean

UNESCO is the UN agency in charge of ocean research. The Intergovernmental Oceanographic Commission (IOC) of UNESCO, founded in 1960 and joined by 150 countries, coordinates global programs such as ocean mapping and tsunami alert system, as well as numerous scientific research projects. The agency is also the guardian of unique ocean places, through 232 marine biosphere reserves and 50 marine World Heritage sites of Outstanding Universal Value. UNESCO leads the United Nations Decade of Ocean Science for Sustainable Development, from 2021 to 2030, which this year is reflected in the organization of several major international summits that will amplify the collective mobilization.

“1 Ocean, the anatomy” campaign

This campaign is led by explorer photographer Alexis Rosenfeld, in partnership with UNESCO for the Decade of Ocean Science for Sustainable Development. Each year, until 2030, expeditions will be carried out across the ocean to bear witness to its assets for humanity, the threats it faces, but also the solutions we can provide.

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