Coral Reef Found Off Tahiti in the Twilight Zone

A coral reef has been found in deep water off the coast of Tahiti in the Pacific Ocean. The coral reef was found to be pristine, undamaged, and in good environmental health. 

The coral reef is rose-shaped. It is part of a larger reef that stretches for more than 3 kilometres long and 70 metres wide at its widest point.  

Laetitia Hédouin and her colleagues at the National Centre for Scientific Research in France undertook diving expeditions off the coast of Tahiti and found the reef. Hédouin said it was a very healthy reef, ‘like a dream come true.’


It was found in deep water about 35-70 metres below sea level near Tahiti. This may be the deepest reef ever found.

Julian Barbière of the UNESCO Intergovernmental Oceanographic Commission, said ‘This reef is also one of the very few we have found at such depths, in what is known as the twilight zone of the ocean.’ 

He said there might be more large reefs in deep water. This is because only 20% of the world’s sea floor has been mapped. By mapping more of the ocean, at even greater depths, researchers hope to understand the best ways to protect and manage these ecosystems.

The researchers found two marine (saltwater) coral species: 1) Porites rus in waters 30-45 metres deep, and 2) Pachyseris speciosa in waters 50-55 metres deep.

The species Porites rus is a coral in the Poritidae family. It forms a cluster of branches, usually in a large hemispherical colony. The species Pachyseris speciosa is a coral in the Agariciidae family. It is a hard coral with rings of concentric ridges that look like plates.

Pachyseris speciosa

Photographer: Martina Nicolls


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