Deep-sea mining: the rush for ocean minerals explained

01Why deep-sea mining is happening now

Deep-sea mining was theoretical for decades. It is now operational. The convergence of three forces — surging demand for battery metals, depletion of accessible terrestrial deposits, and a regulatory window that may soon close — has pushed the deep ocean from scientific curiosity to commercial frontier.

The International Seabed Authority, the intergovernmental body that governs seabed mining in international waters, has issued over 30 exploration contracts covering more than 1.5 million square kilometres of the Pacific abyssal plain. No commercial exploitation has yet been permitted, but the transition from exploration to extraction is the explicit next step in the ISA's roadmap.

The trigger is economic. Cobalt prices, nickel demand, and the scale of the energy transition have made the polymetallic nodules lying on the deep seabed financially attractive for the first time. A nodule is not ore that must be crushed and refined from rock — it is a ready-made concentrate of exactly the metals battery manufacturers need.

02What minerals are on the ocean floor

The deep seabed holds three principal deposit types: polymetallic nodules, seafloor massive sulphides, and cobalt-rich ferromanganese crusts. Each is formed by different geological processes and contains a different metal mix, but all are rich in the elements critical to lithium-ion batteries and renewable energy infrastructure.

Polymetallic nodules are the primary target. These are potato-sized concretions of iron and manganese hydroxides, formed over millions of years around a nucleus, lying loose on the abyssal plain at depths of 4 to 6 kilometres. The Clarion-Clipperton Zone in the central Pacific contains over 21 billion metric tonnes of them, with copper, nickel, cobalt and manganese comprising roughly 30% of their weight.

Seafloor massive sulphides form around hydrothermal vents and are rich in copper, zinc, gold and silver. Cobalt-rich crusts encrust seamounts and contain cobalt, manganese and rare earth elements. Each deposit type presents different extraction challenges and different environmental risks.

03The environmental risks to deep-sea ecosystems

The deep sea is the largest and least-studied habitat on Earth. Scientists estimate that the majority of species in the abyssal plain are undescribed by science. Mining would directly destroy the habitat it covers, and indirectly affect a far larger area through sediment plumes, noise, and toxic discharge.

Collector vehicles would crawl across the seabed, sucking up nodules and the top layer of sediment. The sediment suspended in the water column would form plumes that could travel hundreds of kilometres on deep currents, smothering filter feeders and clouding the water that benthic organisms depend on. Noise from mining operations would propagate efficiently through the deep ocean, affecting marine mammals and other fauna.

The core scientific objection is irreversibility. Deep-sea ecosystems are slow-growing, low-energy, and adapted to stability. A mined area would not recover on any human timescale. The precautionary principle, enshrined in international environmental law, sits in direct tension with the commercial pressure to extract.

04The regulatory vacuum on the high seas

The International Seabed Authority was established under the 1982 UN Convention on the Law of the Sea to manage seabed resources in areas beyond national jurisdiction — the 'common heritage of mankind'. Its dual mandate is to authorise and control seabed mining and to protect the marine environment from its effects.

The ISA has issued exploration contracts since 2001 but has not yet finalised the exploitation regulations that would govern commercial extraction. A clause in the ISA's rules allows any member state to trigger a two-year deadline for finalising these regulations — a mechanism known as the 'two-year rule', invoked in 2021 by Nauru. That deadline passed without finalised rules, leaving the legal status of imminent commercial mining ambiguous.

The regulatory vacuum is not an accident of inaction. It is a structural feature of governing a frontier that no single nation controls. The ISA must balance the interests of mining states, environmental states, land-based mining companies threatened by seabed competition, and the scientific community — all under a treaty framework designed before deep-sea mining was technically feasible.

05Corporate players and their claims

The companies pursuing deep-sea mining range from start-ups to mining conglomerates. The Metals Company, a Canadian-listed firm, is the most visible, holding contracts sponsored by Nauru, Kiribati and Tonga in the Clarion-Clipperton Zone. Others include Belgium's Global Sea Mineral Resources, China Minmetals, and Norway's Loke Marine Minerals.

The sponsorship model is a defining feature of the current regime. A corporation cannot hold an ISA contract directly — it must be sponsored by a state. That has led to a pattern in which small island states sponsor contracts for companies headquartered elsewhere, receiving fees or equity in exchange. Critics argue this structure outsizes the influence of private companies over public resources.

Norway has taken a separate path, opening its own continental shelf — within national jurisdiction, not ISA scope — to deep-sea mineral exploration. That move sidesteps the ISA process entirely and has drawn condemnation from environmental groups and several European partners who argue the scientific basis for the decision is insufficient.

06The renewable energy connection

The case for deep-sea mining is the energy transition. Cobalt, nickel, copper and manganese are all critical inputs for lithium-ion batteries, and the scale of battery production required to electrify transport and storage is unprecedented. Terrestrial supplies are concentrated in a handful of countries, some with poor environmental and labour records.

The argument from mining proponents is that seabed nodules offer a lower-impact source: no rainforest destruction, no child labour in artisanal mines, and a higher metal concentration per tonne of material moved. The counter-argument is that the comparison is false — the deep sea is not a degraded terrestrial mine site, and its biodiversity is both more fragile and less understood.

The renewable energy connection cuts both ways. If the energy transition depends on metals that can only be obtained at unacceptable environmental cost — terrestrial or marine — then the transition itself faces a constraint that no amount of technological optimism can wave away. The question is not whether to mine, but which environmental cost is acceptable and who decides.

07Should we mine the ocean floor

The debate is not between mining and not mining. It is between mining the deep sea, expanding terrestrial mining, reducing demand through recycling and substitution, or accepting a slower energy transition. Each option has costs, and the choice depends on values and evidence that are still in flux.

A growing number of scientists and governments have called for a moratorium or precautionary pause on deep-sea mining until the scientific baseline is adequate. France, Germany, Spain, Chile, New Zealand, Palau, and several other states have supported some form of pause. The UK reversed its position in 2023 to support a moratorium. No commercial mining has begun in international waters.

The decision is ultimately political, not technical. The technology to mine exists. The regulation is being written. The ecosystems are being studied. Whether the abyssal plain becomes a mining district or a protected commons will be decided by the same intergovernmental process that has governed it since 1982 — a process that is now, for the first time, under real commercial pressure.