The Next

Marine explorers have discovered a " pristine" 3km (2-mile) Coral Reef at depths of 30m (100ft) off the coast of Tahiti, French Polynesia .

It is one of the largest discovered at that depth, says the United Nations Educational, Scientific and Cultural Organization, which led The Mission .

Dr Julian Barbiere, from Unesco, said there were probably many more of these ecosystems " we just don't know about".

" We should be working to map them and to protect them, " He Said .

Unesco director general Audrey Azoulay said the " remarkable" discovery extended our knowledge of " what lies beneath".

The Reef was found in November, during a diving expedition to a depth known as The Ocean 's " twilight zone" - part of a

French underwater photographer Alexis Rosenfeld said it had been " magical to witness giant, beautiful rose corals stretching as far as The Eye can see".

" It was like a work of art, " he added.

Coral reefs are among The Ocean 's most threatened ecosystems - Vulnerable to pollution, rising sea temperatures and The Change in chemistry caused by carbon-dioxide emissions dissolving in the water.

Prof Murray Roberts, a leading marine scientist from the University of Edinburgh said The Discovery brought home how much we still have to learn about The Ocean .

" We still associate corals with the shallowest tropical seas but here we find a huge previously unknown Coral Reef system.

" As shallow waters warm faster than the deeper waters we may find these deeper reef systems are refuges for corals in The Future . We need to get Out There to map these special places, understand their ecological role and make sure we protect them for The Future . "

There is currently " no evidence" this reef had been damaged by those pressures and, Dr Barbiere said, its unusual depth was one reason it remained in such a " very good state".

" Generally we find them at shallower depths, " he told Bbc News , because The Algae that lives within the bodies of corals needs light.

" But here we're in a part of The Ocean that is [further] from land, So There is less sediment that ends up in The Ocean here. "

The Discovery provided an important insight into ocean biodiversity, Dr Barbiere said.

" We know that about 25% of marine species can be found in coral reefs, " He Said .

" So The Next stage is to find what species live around this type of reef. "

The Coming months will see further investigation.

Another of The Specialist divers, Dr Laetitia Hedouin, from France's National Centre of Scientific Research, said: " We would expect a reef such as this to take around 25 years to grow and develop like this.

" We think that deeper reefs may be better protected from Global Warming .

" So The Discovery of this reef in such a pristine condition is Good News and can inspire future conservation. "

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