An astonishing collection of cetacean remains dating back five million years has been uncovered on the seafloor of the Diamantine Trench in the southeastern Indian Ocean. The study, published in the journal Nature and completed with the collaboration of paleontologists from the University of Pisa, documents what has been recognized as the world's deepest and most comprehensive whale skeleton deposit. The discovery is the product of multiple dives by Chinese bathyscaphe Fendouzhe at depths ranging from 4,600 to 7,000 meters in the Diamantine Trench, one of the planet's deepest marine depressions. Oceanic trenches, which can reach depths of about 11,000 meters, are some of the most severe, underexplored, and unknown places on Earth. The explorations showed a surprising number and diversity of whale skeletons, both fossilized and contemporary, spread across more than 1,200 kilometers of ocean floor. Many carcasses are still in the process of decomposing and are home to communities of highly specialized organisms that are largely unknown to science. These organisms graze on the organic matter that was transported to the seabed by sunken whales, including that which is preserved within the bones. The bone remains were examined by paleontologists Giovanni Bianucci and Alberto Collareta of the Department of Earth Sciences at the University of Pisa. According to Bianucci, "the majority of the skeletal remains are from beaked whales, which are cetaceans that dive to great depths to hunt. The beaks, which are the anterior part of the skull, are more resistant to degradation over time. Furthermore, several of these remains are coated with a thick ferromanganiferous encrustation, which has aided in their preservation. Numerous beaks belong to two present species, Bowdoin's beaked whale (Mesoplodon bowdoini) and Layard mesoplodon (Mesoplodon layardii), but there are also fossil species, such as the Diamondback whale, a new species that is specifically adapted to this ocean trench". "Dating based on strontium isotopes", continues Collareta, "indicates that the remains of still-living animals are the most recent (from 1.2 million years ago to the present), while those of fossil species date back to 2.4 to 5.3 million years ago. These findings not only corroborate our identifications, but also show that we are dealing with a unique fossil deposit that has been active for over 5 million years and is continuously nourished by the continual deposition of carcasses on the deep seafloor".