A deep-sea abyssal plain covered in polymetallic nodules. Image source: International Seabed Authority, The contribution of the International Seabed Authority to the scientific objectives of the UN Decade of Ocean Science for Sustainable Development (2024)
The International Seabed Authority (ISA), the body established under the United Nations Convention on the Law of the Sea to regulate mining exploration and excavation permits in international seabed areas while ensuring the protection of the seafloor environment, has entered a new round of negotiations this year (2025) on deep-sea mining regulations.
What Is Deep-Sea Mining?
Driven by global demand for technological development and green energy transition, the need for cobalt and nickel has grown steadily. Beyond terrestrial sources, polymetallic nodules found 3,000 to 5,000 metres below the ocean surface contain four metals — cobalt, nickel, manganese, and copper — making them attractive targets for mining companies. Because nickel and cobalt are critical materials for electric vehicle batteries, international pressure has been mounting on the ISA to approve commercial extraction.
These polymetallic nodules are metallic ore formations that grow only a few millimetres to a few centimetres every million years — an extraordinarily slow rate — and are roughly the size of a potato. They are found primarily on deep-ocean abyssal plains far out to sea. Extracting them requires scraping the seabed and using machines to suction the nodules to the surface, where they are transported to shore, crushed, and processed to extract the target metals. In 1989, Germany conducted a study on the environmental impact of deep-sea mining, removing polymetallic nodules at a depth of 4,000 metres and generating sediment plumes. When researchers returned to the site thirty years later, they found that although some organisms had returned, the ecosystem remained severely damaged and homogenised — indicating that the environmental harm caused by mining takes far longer to recover from than previously imagined.
Polymetallic nodules. Image source: ©International Seabed Authority, Secretary-General Annual Report 2024
No member state has yet received an extraction permit, though the ISA has issued numerous exploration licences, most of them concentrated in the Clarion-Clipperton Zone (CCZ) in the central Pacific Ocean. Given that humanity currently understands more about outer space than the deep ocean, whether deep-sea mining is appropriate at this stage remains deeply contentious — a debate that has left more than 2,000 points of disagreement unresolved even after more than a decade of negotiations on a mining code.
Proponents Argue That Deep-Sea Mining Can Support the Green Transition
Electric vehicles, wind power, and solar energy all depend heavily on these critical metals. Supporters contend that because terrestrial mining is highly concentrated in a handful of countries, deep-sea mining could reduce geopolitical risk. They also argue that an insufficient supply of minerals will impede the green transition, and that deep-sea mining can sidestep human rights controversies, create jobs, and reduce environmental impacts on human communities.
Opponents Argue That Mining Should Not Proceed Before the Research Data Is Complete
In truth, there is currently insufficient data to explain how deep-sea mining will affect our lives or how long damaged areas will take to recover. Only about 5% of deep-sea species are known to science, making it extremely difficult to assess the full impact. Deep-sea ecosystems also hold significant research potential for medical biotechnology and genetic data, supporting the development of anti-cancer, antibiotic, and anti-inflammatory drugs. Furthermore, the destruction of deep-sea biodiversity could disrupt carbon and climate cycles, releasing more carbon and accelerating global warming. Opponents therefore argue that extraction should be paused until comprehensive research data is available.
At the same time, alternative technologies that could replace cobalt and nickel are already in development. Lithium iron phosphate (LFP) batteries and sodium-ion batteries — which require neither cobalt nor nickel — are already being used in the electric vehicle industry, and many companies are also researching metal recycling technologies.
Much of the deep-sea ecosystem remains to be explored. Image source: International Seabed Authority, The contribution of the International Seabed Authority to the scientific objectives of the UN Decade of Ocean Science for Sustainable Development (2024)
Without Consensus, Why Is the ISA Still Rushing to Push Through Mining Permits?
The ISA has been accelerating its push for extraction permits in recent years. Beyond pressure from the private sector — eager to satisfy investors — and from green-transition advocates, the so-called two-year rule has become a key driver of forced action. Originally designed to prevent the ISA from dragging its feet on decisions, the rule stipulates that if a country applies for a commercial extraction permit, the ISA must finalise a mining code within two years; otherwise it must consider approving that country's application. This provision has since been exploited by proponents as a loophole — now widely referred to as the "two-year loophole."
In 2021, the Pacific island nation of Nauru, acting on behalf of Canadian mining company The Metals Company, formally submitted an extraction permit application to the ISA, triggering the two-year rule and demanding that a mining code be completed by 2023. This sparked widespread international debate. Beyond the lack of research data and the absence of international consensus, the extraction technology itself is still far from mature: withstanding the extreme cold and pressure of the deep ocean and transporting these heavy mineral deposits from remote ocean locations back to shore are formidable challenges. The economics are also expected to be unfavourable, with costs so high that the operation may not be competitive on the open market. The ecological damage would extend well beyond the deep sea — sediment plumes generated by mining could spread to coastal areas, threatening coastal ecosystems and economies.
Deep-Sea Mining: Hope or Hazard for the Resource Transition?
To date, 32 countries have opposed proceeding with deep-sea mining before research data and policy frameworks are complete. Major corporations including Google, Volvo, Samsung, and BMW have pledged not to use materials sourced from deep-sea mining. Countries in support include Norway, China, Russia, India, Nauru, and Kiribati.
As the world pursues a sustainable transition, deep-sea resources have emerged as a new frontier — yet the deep ocean also remains one of the most scientifically underexplored regions on Earth. In the absence of clear ecological impact assessments and robust regulatory mechanisms, how humanity chooses to navigate this "deep-sea uncertainty" is ultimately a test of the values we place on development versus protection.
Further Reading
