Deep-Sea Mining

The deep ocean is among the least understood parts of the planet. Below 200 metres, where sunlight no longer reaches, life organizes itself around conditions that have little in common with the shallow coastal systems most ocean science has studied. The abyssal plains that cover much of the ocean floor at depths of 4,000 to 6,000 metres are among the most remote and least surveyed environments on earth. The organisms that live there, many of them still unnamed, have adapted over millions of years to extreme pressure, near-freezing temperatures, and near-total darkness. The ecological relationships that sustain those communities are poorly mapped, and in most areas nobody has established the baseline against which change could be measured. This is the environment that a small number of companies now propose to mine.

The mineral case is straightforward. The abyssal plains of the Pacific, Atlantic, and Indian Oceans hold polymetallic nodules, potato-sized formations that accumulate on the seabed over millions of years and carry manganese, nickel, cobalt, and copper. Battery technology, electric vehicles, wind turbines, and other energy transition infrastructure need those minerals in quantity. Land-based deposits of several of them sit in politically unstable regions or in the hands of a small number of producing countries. The nodule fields of the Clarion-Clipperton Zone in the Pacific, one of the most extensively explored areas, are estimated to hold more of some of these minerals than all known land-based reserves combined. The economic logic for extraction is not difficult to articulate.

The International Seabed Authority manages the governance framework for mining the international seabed, established under the United Nations Convention on the Law of the Sea to administer the Area, meaning seabed beyond national jurisdiction, on behalf of humanity as a whole. The ISA has issued 32 exploration contracts to 22 contractors, including state entities and private firms from China, Belgium, the United Kingdom, and elsewhere. It has not approved any commercial exploitation contract. The Mining Code that would govern commercial extraction has been under negotiation for years and remains unfinished. As of the ISA's 2025 meetings, the negotiating body was split between states pushing to finalize the rules so exploitation can proceed and a growing bloc calling for a moratorium or precautionary pause. By 2025, more than 40 countries had formally supported some form of pause, including France, Germany, the United Kingdom, Chile, and Brazil. Fiji, Samoa, and Vanuatu have also called for one, and they are the states closest to the water in question. Canada's position is precautionary and stops short of a formal moratorium call. All of this runs alongside the separate governance work of the High Seas Treaty.

The most commercially aggressive actor in the field is The Metals Company, a Vancouver-based firm operating through exploration contracts sponsored by Nauru and Tonga. TMC reports having invested more than US$500 million over the past decade and has positioned itself as the company closest to commercial readiness. In June 2021, Nauru triggered a provision in the UNCLOS framework that required the ISA to finalize exploitation rules within two years or be obligated to consider a mining application regardless. That deadline passed in July 2023 without finalized rules and without a commercial license being issued. In 2025, TMC changed approach, and its US subsidiary applied to the National Oceanic and Atmospheric Administration for exploration and commercial recovery permits under US domestic law, an attempt to proceed outside the ISA process entirely. That move drew criticism from states and international legal scholars who argued it circumvents the multilateral framework UNCLOS established.

The ecological unknowns sit at the center of this debate. Nodule mining would physically remove the nodules, disturb seabed sediment across wide areas, and generate sediment plumes that redeposit beyond the mined zone. Nodules are hard substrate in an environment where hard surfaces are scarce, and the communities that colonize them, including corals, sponges, and hundreds of invertebrate species, depend on their presence as habitat. Recovery from physical disturbance at abyssal depths, where it happens at all, runs on timescales measured in decades to centuries. Disturbance experiments conducted in the 1970s and 1980s still show persistent ecological effects. A 2025 Nature study found that recovery evidence from nodule-field disturbances remains limited and that biological effects over long timescales are poorly understood.

A 2024 study added a further complication. Researchers reported unexpected oxygen increases at polymetallic nodule-covered seabeds, suggesting the nodules may play a geochemical role nobody had identified. The finding is contested and the scientific debate around it continues, though the existence of that debate is itself the point. The nodule fields are not understood well enough for the consequences of removing them to be predicted with confidence. That is a plain observation about making decisions under uncertainty, at a scale and in an environment where mistakes cannot be undone.

The institutions that price risk have reached their own view. In July 2025, 41 financial institutions representing more than €3.8 trillion in assets reissued a statement urging governments not to permit deep-seabed mining until environmental, social, and economic risks are better understood and alternatives explored. The United Nations Environment Programme Finance Initiative has stated that in its current form there is no foreseeable way that financing deep-sea mining can be consistent with the Sustainable Blue Economy Finance Principles. Among insurers, Swiss Re, Hannover Re, Zurich, and Vienna Insurance Group have all been reported as excluding deep-sea mining from their underwriting portfolios.

Insurers hold better information about physical ocean risk than anyone lending against it. Their judgement does not stay in the insurance market. Cover against physical loss is a standard prefunding condition, so the certificate has to be on file before the lender will release loan proceeds, and where no insurer will issue one the advance simply never happens. The lender never has to reach a view on abyssal ecology. Somebody else already did, and the loan stops on a checklist item.

The governance problem works the same way. A mining operation in the Area depends on a regulatory framework still being negotiated, on a sponsoring state relationship whose terms have already been renegotiated once in the TMC and Nauru case, and on an international legal architecture whose interpretation is actively disputed. A lender cannot write a covenant against rules that have not been drafted, and cannot take security in a license that does not yet exist. The value of the investment rests on assumptions about regulatory outcomes, and nobody can stand behind them.

So the minerals are genuinely needed for the energy transition, the governance framework for reaching them is unresolved, and the ecological consequences of large-scale nodule mining are not adequately understood. Those three things are usually presented as the whole question, to be settled by the ISA in some future session. What the last few years suggest is that a good deal of it has been settled already, by underwriters and lenders working through their ordinary conditions rather than by anyone taking a position on the deep sea. Whether that is a good way to decide something this consequential is a separate question, and worth asking.