As part of a global seabed-mapping mission, marine explorers found, in the French Polynesia, what is a pristine coral reef that stretches over 3 kilometers, sitting at a 30 m depth. 

The coral reef, described by French marine photograher Alexis Rosenfeld as "magical," lies off the coast of Tahiti, French Polynesia. The coral reef is one of the largest discovered at the depth of 30 meters, according to the UN Educational, Scientific and Cultural Organization, which sponsored the mission that led to the discovery. 

"We should be working to map and protect them," said UNESCO's Dr. Julian Barbiere, referring to the many ecosystems that are still yet to be discovered. 

The depth of the exploration is what is known as the "twilight zone," for despite the depth and darkness of the ocean, there is just enough light for algae to survive. 

The coral reef was discovered in November, and its discovery will extend scientific knowledge.

Rosenfeld weighed in on the discovery, saying that it has 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.

Considering the depth at which the reef was found, scientists contend that there is still much to be learnt about coral reefs. 

A prominent marine scientist at the University of Edinburgh, professor Murray Roberts, said "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," Roberts said. 

According to Barbiere, generally, reefs are found at shallower depths, since algae needs light. "So the next stage is to find what species live around this type of reef."

Dr Laetitia Hedouin, a specialist diver from France's National Centre of Scientific Research, said they "would expect a reef such as this to take around 25 years to grow and develop like this," and that "deeper reefs may be better protected from global warming." 

Hedouin said that the discovery is "good news" and can inspire future conservation. 

Global warming is destroying coral reefs

A report by Global Coral Reef Monitoring Network (GCRMN) reveals the "catastrophic consequences of global warming" while declaring that there is still hope in saving coral reefs if actions are undertaken quickly.

According to one of the report’s editors, David Obura, coral reefs can act like "canaries in the coal mine by telling us how quickly it can go wrong." He added that a 14% decline in the reefs' area is a cause "for deep concern."

Serge Planes, a research scientist, announced that since 2009, the coral reefs have been in "constant decline at the global level."

Coral reefs provide a home for fish, that is, "protein to hundreds of millions of people." In addition, their limestone branches provide protection to coasts from storms, according to the report.

The report stressed that if the world limits global warming, coral reefs can regenerate, adding that reducing pollution caused by sewage, agricultural runoff, and industrial chemicals is also a critical factor.

Read more: Planet Earth has lost more than half of its coral reefs since 1950