Chinese scientists uncover world’s deepest whale fossil graveyard in Indian Ocean

Chinese scientists have mapped what appears to be the deepest and largest known graveyard of whale fossils in the world, a vast stretch of the southeastern Indian Ocean where carcasses and whale-fall ecosystems run along the seafloor for about 1,200 kilometers. The site sits in the Diamantina Zone at depths from about 4,616 to 7,001 meters, with the deepest active whale-fall ecosystem recorded at 6,789 meters. One researcher said the discovery was “far beyond anything we had imagined.”

The expedition found 485 whale fossil sites and five active whale falls during 32 dives in 2023 aboard the crewed submersible Fendouzhe. Researchers from the Chinese Academy of Sciences’ Institute of Deep-sea Science and Engineering worked with scientists from the University of Pisa and New Zealand’s National Institute of Water and Atmospheric Research. The oldest whale bones at the site date to about 5.3 million years ago, and the team collected 43 fossil specimens spanning roughly 120,000 to 5.26 million years.

That makes the site more than a museum of dead whales. Whale falls create concentrated deep-sea habitats that can support scavengers, microbes and a whole food web built around decaying bone and soft tissue. Around the remains, researchers observed bone-eating worms, brittle stars, sea cucumbers, squat lobsters, tubeworms, jellyfish and clams, several of which may represent undescribed species. The discovery also includes a new species of extinct beaked whale, adding a fresh data point to the evolutionary history of deep-diving cetaceans.

Scientists say the find matters because the deep ocean preserves evidence that is usually scattered, hidden or consumed before it can be studied. The Diamantina Zone may contain more than 10 million whale carcasses, representing a major carbon sink that has so far been poorly quantified. The researchers estimated the site could hold about 6.7 million tons of sequestered carbon, a reminder that marine ecosystems are not just biological systems but part of the planet’s long-term carbon budget.

The geology helps explain why so many remains ended up in one region. The Diamantina Fracture Zone is a rift valley linked to the breakup of Australia and Antarctica about 50 million years ago, and its V-shaped geometry may have helped funnel whale carcasses into the same corridor over time. For scientists studying mass die-off events, ocean food chains and how life survives extreme darkness, pressure and low oxygen, the site offers an unusually dense archive of deep-time ocean history. Nick Pyenson of the Smithsonian Institution called the find “something novel” and said it was “really neat to see,” while Giovanni Bianucci said it helps explain how life adapts to the harshest conditions in the deep sea.