The number 0.001 percent has a subtle humble quality. The percentage of Earth’s deep seafloor that humans have ever seen up close is the kind of number that takes some time to come to terms with. Not detected by sonar from a research vessel’s hull, not mapped by satellite, but truly observed by cameras or human eyes. a region about the size of Rhode Island. That figure feels more like an admission than a data point on a planet that is 71% ocean and 90% deep sea.
In May 2025, a study that was published in Science Advances made this clear. The vast majority of the ocean floor is still essentially unknown, according to researchers from the Ocean Discovery League who examined records from about 44,000 deep-sea dives carried out since 1958—nearly seven decades of submersibles, remotely operated vehicles, and scientific ambition. The extent of our ignorance may be the most obvious discovery in recent oceanography.
This is unsettling in part because of the timing. Scientists and 32 nations demanded a moratorium after the Trump administration signed an executive order last month that would expedite approvals for seabed mining of vital minerals in the deep ocean.
The minerals in question, manganese, cobalt, and nickel, are found in nodules dispersed throughout abyssal plains such as the Clarion-Clipperton Zone, a Pacific seafloor stretch between Hawaii and Mexico that is about the same width as the continental United States. Researchers at the Natural History Museum have discovered that about 90% of the species in that zone are still unnamed before any rover descends to collect them. There are thought to be between 6,000 and 8,000 species waiting to be found there, and even that number is probably underestimated.
Observing all of this, it seems as though humanity is progressing more quickly than its own body of knowledge can sustain. Making assumptions about all terrestrial life on Earth based on observations of a smaller land area than the city of Houston is a difficult comparison, according to Katy Croff Bell, lead author of the Science Advances study. That is essentially the intellectual foundation upon which decisions about deep-sea policy are currently being made.
The issue is made worse by the bias in the scant data that is available. Within 200 nautical miles of just three nations—the United States, Japan, and New Zealand—more than 65% of visual observations have occurred. Ninety-seven percent of all deep-sea submergence records come from five countries. The image of the deep ocean that science has created is more of a series of close-ups taken in the same three neighborhoods that have been uncertainly extrapolated outward than a global portrait.
By definition, the majority of what exists in those unseen depths is conjecture. The creatures from the deep sea that have already been cataloged, such as ghostly white anemones anchored to nodule fields that haven’t changed in millions of years, gulper eels with expandable jaws, and vampire squid drifting through perpetual darkness, strain credulity. Only in 1977 were hydrothermal vents found to sustain entire ecosystems that rely on chemical energy instead of sunlight, a discovery that completely changed preconceived notions about the possible locations for life. It’s difficult not to wonder what comparable discoveries remain undiscovered and unnamed 5,000 meters below the surface.
Nor is the deep ocean passive scenery. It absorbs about 30% of atmospheric carbon dioxide and about 90% of the excess heat trapped by human greenhouse emissions. According to Bell, the current state of civilization on Earth’s surface would probably not be possible without this function. No mineral deposit can readily offset the risks associated with upsetting those ecosystems without first understanding them.
A few years ago, Bell asked in private, “How much of the deep sea have we actually seen?” — has a response now. Not very much. However, choices about its use cannot be postponed indefinitely. The baseline data required to safeguard it, control it, or even accurately characterize it is still mostly lacking. There is more to that than just a scientific gap. It has to do with governance.
