Four kilometres down in the central Pacific, between Hawaii and Mexico, there is a plain of mud scattered with dark, lumpy rocks about the size of apples or potatoes. Those rocks hold metals the battery and electric-vehicle industries want. The problem is that the same seafloor is home to animals we have barely begun to count, and the clocks don’t match. The commercial race runs on years. Recovering the seabed, and the science needed to understand it, runs on decades.
We are not marine biologists, geologists, or policy specialists, and nothing here is advice on how any government or company should act. This is our reading of the published research and the public record. Much of that research comes from a small number of test sites, so it describes patterns scientists have measured, not settled verdicts about how mining at full scale would play out.
The prize on the seafloor
The rocks are called polymetallic nodules, and they form slowly. The International Seabed Authority’s own fact sheet describes growth measured in millimetres per million years. A nodule you could hold in one hand took longer to form than most rock formations on land. They reach up to 20 centimetres across, and they sit loose on the surface of the mud rather than buried in it.
The reason anyone cares is what’s inside them. A USGS review puts a conservative estimate at 21.1 billion dry tonnes of nodules in the Clarion-Clipperton Zone, the largest known nodule field on Earth. For many important metals, the review found, there is more locked in those nodules than in the reserves known on land. The International Seabed Authority’s figures show the scale: roughly 6 billion tonnes of manganese, 270 million tonnes of nickel and 44 million tonnes of cobalt, more than the known land totals for all three.
The pitch, and the race the ISA opened
The case for mining is easy to state. The world wants cobalt and nickel for batteries. Much of today’s supply comes with real environmental and labour costs on land. And the nodules are just sitting there to be picked up rather than dug out. That pitch has real force.
It has also opened a race. The International Seabed Authority, the UN body that governs mineral activity in international waters, has issued exploration contracts across the seabed, 19 of them for nodules in the Clarion-Clipperton Zone. No contract to actually mine has been granted yet, mostly because the rulebook for extraction is still unfinished. The firm pushing hardest to begin is a Canadian company, The Metals Company, which has publicly campaigned to start.
The scientists watching this feel the moment approaching too. In a December 2025 study of a large mining trial, the authors wrote that deep-sea mining in the zone is “at a critical juncture, as the industry looks to move beyond the exploration phase and into commercial exploitation”. That framing is the authors’ own, and some of them disclose funding ties to prospective mining companies. But on the timing, they and the industry agree: the exploration phase is ending.
The hole in the argument
This is where the pitch hits a problem it can’t easily talk its way around. We are proposing to industrialise a place we have not finished describing.
A 2023 checklist in Current Biology, the first full survey of the animals living on the zone’s seabed, counted 5,578 recorded species and found only 436 of them had formal scientific names. That leaves about 92 per cent new to science, with the real total likely somewhere between 6,000 and 8,000 species or more. One of the coauthors, Muriel Rabone of the Natural History Museum in London, told Science News that “the diversity down there does surprise me.” A biologist who has read the checklist is saying the place is richer than she expected.
The zone covers roughly twice the area of India. So the question isn’t whether mining would harm a few striking creatures. It’s whether we can weigh the cost of disturbing an ecosystem when nine in ten of its inhabitants don’t yet have a name, let alone a studied role.
What disturbance actually does, and for how long
Two recent studies give the clearest picture yet of what happens after the machines pass, and both point the same way: the effects fade slowly.
The first revisited a test site from 1979, where a collector had been run across the seabed. Scientists went back 44 years later. The lead author, Daniel Jones of the UK’s National Oceanography Centre, described what they found: “Forty four years later, the mining tracks themselves look very similar to when they were first made, with an 8-metre-wide strip of seabed cleared of nodules and two large furrows in the seafloor where the machine passed.” That is one 1979 test site, and a modern commercial machine would work differently. But the marks it left were still clear four decades on.
Jones was careful not to say nothing had come back. “The numbers of many animals were reduced within the tracks but we did see some of the first signs of biological recovery,” he said. Note how tentative that is: first signs. He put the broader takeaway to Carbon Brief this way: “The key finding, really, is that deep-sea mining has really long-term effects that last for multiple decades. They’re clear physical and biological changes.” Those words describe what one 44-year-old site showed, not a proven rule for every future operation.
The second study looked at something closer to the real thing. After a 2022 trial that recovered over 3,000 tonnes of nodules at 4,280 metres depth, researchers compared the animal life inside the mining tracks with the surrounding seabed. Inside the tracks, the team found a 37 per cent drop in total animal numbers and a 32 per cent drop in the range of species.
Deciding before we can know
Set the two clocks next to each other and the mismatch is the whole story. The commercial timeline is the few years it takes to finish a rulebook and float a machine. The recovery timeline, on the evidence of the 1979 site, runs for decades and may run longer. The scientific timeline, the plain work of naming and understanding the animals that live there, has barely started: most of the species have no name at all.
None of this settles whether the nodules should be lifted. The metals are real, the demand is real, and mining them at sea has to be weighed against the costs of mining them on land, which are not small. What the research does make hard to accept is the idea that we already know enough to make that trade with confidence. Two test sites and a species checklist that is 92 per cent incomplete are a starting point, not an answer.
Our read, as far as we can tell, is not for or against. It’s that the questions have an order. What lives there, what a full-scale commercial machine actually does to it, and how long the seabed takes to recover are all things you would want answered before the first mining contract is signed, not after. The worry isn’t that the answer will be bad. It’s that we are being asked to decide before we can know what we’re deciding about.
