Chinese researchers have identified the largest known whale graveyard on Earth, located on the seafloor of the Indian Ocean west of Australia. The discovery, detailed in the journal Nature, reveals a vast area spanning approximately 1,200 kilometers and reaching depths of up to 7,000 meters where nearly 500 whale skeletons — some over 5 million years old — were found.

The research team, using the manned submersible Fendouzhe, conducted 32 dives in 2023 to explore this extensive site, known as the Diamantina Zone. The submersible, capable of carrying up to three people, collected fossil samples with robotic arms while documenting a diverse array of deep-sea life thriving on the sunken whale remains. Among the finds was a previously unidentified extinct species of beaked whale.

Lead author Xiaotong Peng of the Chinese Academy of Sciences described the scale and scope of the find as “astonishing.” Whale falls, the carcasses of whales that sink to the ocean floor, have long been known to support unique ecosystems, but the magnitude and age range found here surpassed expectations. The researchers suggest that the area may act as a natural funnel for carcasses due to its distinctive V-shaped trench and may also be a preferred foraging zone for whales, contributing to the accumulation.

The site’s ecological importance is underlined by the presence of numerous species including jellyfish, worms, snails, crustaceans, brittle stars, and bivalves, many of which rely on the nutrients provided by the decomposing whale tissue. Extrapolating from the fossil count, scientists estimate that the number of whale carcasses in the Diamantina Zone could exceed 10 million, collectively storing an estimated 6.7 million tons of sequestered carbon. This nutrient supply parallels that of hydrothermal vents, creating complex ecosystems on the otherwise resource-limited deep-sea floor. Some species observed also inhabit hydrothermal vents and cold seeps, hinting at possible ecological connectivity between these environments.

The research team’s findings have drawn praise from experts worldwide. Craig Smith, a University of Hawaii oceanographer who discovered the first whale fall in 1987 but was not involved in this study, described the magnitude of the fossil record and the identification of a new whale species as pivotal for understanding whale evolution and historical distributions. Florida State University researcher Amy Baco-Taylor called the discovery “remarkable” and suggested it could offer new insights into whale mortality, noting the unusual concentration of carcasses in one area.

Paleontologist Stephen Godfrey compared the finding’s significance to the landmark discovery of hydrothermal vents in 1977 and emphasized the potential for additional deep-sea surveys to uncover other whale graveyards globally. Fossil evidence indicates similar sites might exist near South Africa, the Iberian Peninsula, and the Crozet Islands.

The study provides a rare glimpse into deep-sea ecosystems shaped by whale falls, highlighting their role in marine carbon cycling and biodiversity over millions of years. The researchers hope future expeditions will expand understanding of these mysterious underwater necropolises.