In the southwest Pacific, off the coast of one of the tropical Solomon Islands, a giant structure located beneath the water’s surface has been identified as the largest known coral in the world.

Visiting the isolated site in mid-October, a team of scientists and filmmakers from National geographic I thought the object was so large that it must be the remains of a shipwreck.

But when the underwater cinematographer Manu San Felix jumped into the water to take a closer look, he was amazed by what he saw.

“I vividly remember jumping and looking down, and I was surprised,” he told reporters at a briefing. Instead of a shipwreck, San Felix had stumbled upon the largest coral ever discovered. “It’s huge,” he said. “The size is close to that of a cathedral.”

The coral, which is found a few hundred meters from the east coast of Malaulalo Island, has been identified as the species Pavona clavus. It measures 34 meters wide by 32 meters long, making it larger than a blue whale, and is estimated to be 300 years old.

The discovery was a “happy accident,” says Enric Sala of National geographic‘s Pristine Seas Project, which aims to inspire governments to protect ocean ecosystems through exploration and research. It is by far the largest coral colony ever discovered, easily beating the previous record holder – a giant Porites colony found in American Samoa in 2019, measuring 22.4 meters in diameter and 8 meters in height.

Over the past two years, record ocean temperatures have triggered a wave of coral bleaching across the world. But as other reefs around the Solomon Islands show signs of bleaching, Sala says the enormous P.clavus the coral looks healthy. It’s a vital habitat for ocean life, he says, providing shelter and food for fish, shrimp, worms and crabs. “It’s like a big patch of old-growth forest.”

But coral is not immune to ecological threats, from local pollution and overfishing to global climate change. Sala says he would like to see more marine protected areas (MPAs) created to protect marine life from local pollution, alongside global action to combat climate change. “Protecting the reef cannot make the water cooler, nor can it prevent the ocean from warming,” he says. “We have to solve this problem, we have to reduce carbon emissions. But MPAs can help us buy time by making reefs more resilient.