Marine biologists have unearthed a spectacular coral reef off the coast of Tahiti in the South Pacific. The 3km-long reef lies at a depth of 30 metres. The scientists believe the array of corals and ocean vegetation contains previously undiscovered marine species. They have already found hundreds of rose-shaped coral, some of which measure over two metres in diameter. Deep-sea diver Alexis Rosenfeld said he was stunned when he came across the reef. He wrote: "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." Scientist Laetitia Hedouin said: "It's a very healthy reef. In the middle of the biodiversity crisis, this is very good news."

Scientists say the location of the Tahiti reef means it is in pristine condition. Most of the world's reefs are in warmer waters. This makes them prone to the bleaching effects of global warming. Tahiti's reef is deep enough to protect it from bleaching. There is still sufficient sunlight at 30 metres for coral to grow and reproduce. UNESCO said: "We think that deeper reefs may be better protected from global warming." It believes the Tahiti reef is "one of the most extensive healthy coral reefs on record". It added that more mapping of the deep ocean needs to be undertaken. It said: "We know more about the surface of the Moon or the surface of Mars than the deeper part of the ocean."