Eighty steel boxes, each roughly the size of a microwave oven, were lowered to the bottom of the Pacific Ocean between late 2020 and the end of 2022. When researchers finally finished sorting everything inside, they counted 4,350 animals belonging to 788 distinct species. The overwhelming majority of those species have never been formally named. The samples came from the Clarion-Clipperton Zone, a stretch of abyssal plain between Hawaii and Mexico that is roughly the size of the contiguous United States, and the results, published in Nature Ecology & Evolution, represent one of the most detailed species-level inventories ever assembled for a region at the center of the global debate over deep-sea mining.
What 80 box cores revealed
The 80 sediment samples were collected across four expeditions spanning roughly two years. Of the 4,350 macrofauna pulled from the mud, 3,826 could be identified to species level. The remaining roughly 500 were either too damaged during collection or belonged to groups so poorly known that taxonomists had no reference material for comparison.
The sampling was not random exploration. It was tied directly to a collector-vehicle trial operated by The Metals Company’s subsidiary NORI and its partner Allseas in 2022, a test run of the machinery designed to scrape polymetallic nodules from the seafloor if full-scale mining goes ahead. That connection gives the dataset unusual weight: these are the actual organisms living in the path of proposed industrial equipment.
Many of the animals recovered live in and around the nodules themselves. These potato-sized lumps of manganese, nickel, cobalt and other metals sit loose on the abyssal plain and take millions of years to form. In a landscape that is otherwise soft mud, nodules provide the only hard surface for attachment. Removing them would erase habitat that cannot be replenished on any human timescale, and the box-core inventory makes clear just how much life depends on that habitat.
A seafloor we have barely looked at
The sheer number of unnamed species in 80 small samples becomes even more striking against a broader statistic. A separate analysis published in Science Advances found that only about 0.001 percent of the deep seafloor has been visually observed over the past 70 years, an area roughly equivalent to Rhode Island. The original article did not provide a direct link to the specific paper, and no DOI or author name is available from the source material, so the statistic is reported here as attributed in the original study without a direct link. If a handful of box cores from a single mining-test zone can turn up 788 species, the true biodiversity of the wider Pacific abyss almost certainly dwarfs anything in existing databases.
The International Seabed Authority (ISA), the United Nations body that regulates mineral activities in international waters, maintains a repository called DeepData that is meant to aggregate biological information from contractor surveys and research expeditions. But a peer-reviewed assessment of that database, published in the journal Database, flagged serious shortcomings in data quality, standardization and reuse. The biological records in DeepData often lack the taxonomic resolution found in independent studies, meaning the official data infrastructure may systematically undercount the species present in areas slated for extraction.
That mismatch has real consequences. Environmental impact assessments for mining contracts draw on ISA data. If those records portray the abyss as sparsely populated or dominated by a handful of widespread species, large-scale disturbance can appear more acceptable than peer-reviewed fieldwork suggests it should be.
What scientists still do not know
The 788 figure counts only the specimens that could be identified. Factor in the roughly 500 that could not, and the true species count from these same samples is likely higher. Researchers have not yet released complete species-by-species identification tables for public review, and the taxonomic work behind many of the 788 designations is ongoing. Separate studies from the same expeditions, including new taxa described in the Zoological Journal of the Linnean Society, have begun the formal naming process, but that work typically takes years.
Recovery is another open question. The 2022 collector trial disturbed sediment and removed nodules from test tracks on the seafloor. Independent verification of how quickly, or whether, macrofaunal populations bounce back has not appeared in contractor reports as of June 2026. Mining vehicles are expected to create persistent sediment plumes and strip nodules wholesale, so the relevant question is not just whether animals return but whether the original community structure and ecological function can be restored. The four expeditions covered about two years; capturing the fate of slow-growing and rare species will require monitoring over decades.
There is also the widely cited claim that 90 percent of deep-sea life remains unknown. No single peer-reviewed paper pins that figure to a specific methodology, but the evidence from the CCZ strongly supports the underlying idea. When the vast majority of species in a rigorous new inventory lack formal names, and when less than a thousandth of a percent of the deep seafloor has been visually surveyed, the proportion of undescribed life is plainly enormous. The precise number is an approximation, but the direction is not in dispute.
Why the gaps matter for the Mining Code deliberations
The ISA has been working toward a regulatory framework, known as the Mining Code, that would govern commercial extraction in the CCZ and other international seabed areas. Deliberations have stretched over years, and as of mid-2026 no final code has been adopted, though pressure from contractor nations and companies continues to build. Decisions made in the coming sessions will determine whether mining can proceed and under what environmental safeguards.
The strongest evidence in this story comes from the Nature Ecology & Evolution paper itself. It provides exact specimen counts, species totals and a clear description of sampling methods tied to a specific industrial trial. The data were collected, sorted and analyzed by the authors, not compiled from secondary reports. Any reader evaluating the state of CCZ biodiversity should weight those numbers heavily, especially where they conflict with coarser contractor summaries.
The DeepData assessment exposes structural weaknesses in the information pipeline regulators depend on. When contractor surveys report fewer species than independent box-core studies from the same region, the gap may reflect differences in sampling effort, taxonomic expertise or reporting standards rather than deliberate understatement. But the practical effect is the same: the official record paints a less biodiverse picture than the best available fieldwork consistently finds.
Taken together, the lines of evidence point in one direction. The abyssal plains targeted for mining are not biological deserts. Current knowledge is too fragmentary to predict the full consequences of industrial disturbance. And the decisions that will shape the fate of the Clarion-Clipperton Zone are being made with only a sliver of the relevant biological information in hand. Until that gap narrows, any assurance that environmental risks are well understood deserves serious scrutiny.
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*This article was researched with the help of AI, with human editors creating the final content.
