Australia’s most famous coral resides on its Pacific coast. The Great Barrier Reef is amazing, to be sure, and a bellwether of how climate change is impacting reefs around the world. But there’s a reef hidden in the depths of the Southern Ocean off Australia’s south coast that could unlock a much more profound secret about climate change and the entire ocean. And until recently, it remained completely unexplored.

Over the course of a month, a team of researchers probed the deep-sea canyons that jut out from Australia’s southern continental shelf like fingers plunging into the chilly Southern Ocean. Delicate corals exist in the waters that may only reach 10 degrees Celsius (50 degrees Fahrenheit), clinging to the walls of the canyons and crawling over plateaus. The researchers on the R/V Falkor sent a remotely operated vehicle (ROV) down to those depths to collect samples of both living and fossil corals while capturing stunning 4K video from the deep sea.

Researchers had a good guess these unique ecosystems were sitting at the bottom of the sea in the area after a 2015 expedition in somewhat nearby Perth Canyon, but it was a crapshoot of just what exactly they would find. Instead, the trip yielded a wide array of coral samples that could help the researchers understand this part of the ocean and the waters that flow through it. 

Knowing the ways in which water wends its way from Antarctica slowly north on a current across the Southern Ocean can also help them understand the whole system. In an era of climate change, oceans are taking up 90 percent of all excess heat that carbon pollution traps and also sequestering massive amounts of said carbon (which, FYI, is driving ocean acidification).

And of all the oceans, the Southern Ocean is perhaps the most important, sucking up 40 percent of all of humanity’s emissions each year. Because the waters the deep-sea corals inhabit are more corrosive than surface waters, the research could also help other coral researchers looking at how to conserve warm water corals in more acidic oceans.