Coral welcomed to the twilight zone

Image: Karl Callwood on Unsplash

Scientists have discovered a giant coral reef off the coast of Tahiti, in what is known as the twilight zone, 30 meters below sea level.

The coral reef is three kilometres long and 30 to 65 metres wide - making it which is one of the world's largest unspoiled reefs. The majority of coral reefs across the world form at depths of up to 25 meters in water, while the reef in Tahiti is located in the twilight zone of the Pacific Ocean - recognised as a depth between 30 - 120 metres.

Dr Laetitia Hédouin and her colleagues from the French National Centre for Scientific Research discovered the reef during a 200-hour diving expedition in November 2021, as part of a global seabed-mapping mission led by UNESCO (United Nations Educational, Scientific & Cultural Organisation). According to UNESCO, the newly discovered reefs are in near perfect condition - allowing researchers important insights into ocean biodiversity.

"Millions of people rely on the so-called ecosystem services provided by coral reefs for their livelihoods. We need coral reefs for fisheries, for tourism, even for coastal protection.”

Dr Laetitia Hédouin, French National Centre for Scientific Research

Currently only around 20% of the ocean floor has been mapped, demonstrating how much of the ocean — which covers more than 70% of Earth’s surface — still needs to be explored.