More than 20 financial institutions have publicly said they will not fund deep-sea mining, an activity many scientists warn could inflict irreversible harm on ocean ecosystems. But a DW investigation using company filings compiled by Greenpeace Germany and investment data from the Anti‑Corruption Data Collective (ACDC) shows that some banks and investors have nonetheless put at least $684 million (€581 million) into companies linked to the sector.
Hundreds of millions of dollars flow to firms racing to extract nickel, cobalt and copper from polymetallic nodules found thousands of meters below the surface — a part of the planet that remains largely unknown. Less than 0.001% of the seafloor has been explored. Among the investors identified are major global banks, including Deutsche Bank, UBS, Credit Suisse, Crédit Agricole and BNP Paribas.
Some institutions say their restrictions apply only to direct financing of specific mining projects, not to buying equity in companies preparing to mine. Campaigners call this a loophole, accusing those banks of greenwashing: publicly refusing project finance while still investing in companies that enable or plan seabed extraction. Greenpeace and other activists argue that careful wording and small-print exceptions let financiers avoid reputational risk without meaningfully changing overall investment behavior.
There are exceptions. Norway’s Storebrand, one of the country’s largest financial groups, has divested millions from firms linked to deep-sea mining, citing the precautionary principle and saying it will not invest in companies involved in the practice until scientific knowledge improves. By contrast, Goldman Sachs — which markets environmental, social and governance (ESG) investment strategies — holds roughly €187 million of stakes in companies tied to deep-sea mining activities.
Public money and pension capital are implicated as well. DW’s review found investments by funds and vehicles that draw on public pension resources. The private-equity fund Triton IV, which pooled money from public pension funds across Europe and Canada, managed subsea firms DeepOcean and Adepth Minerals until spring 2025 before those businesses were sold to a new entity managed by Triton; the firm disputes characterizations that its holdings amount to seabed-mining investment. Campaigners say pension funds, which invest on behalf of citizens’ futures, should factor in environmental risk and adopt exclusions against deep-sea mining — but so far none have done so.
Some governments are taking firmer positions. Around 40 countries support moratoriums or precautionary pauses on mining in international waters, and Norway has agreed not to issue mining licences in its national waters until at least 2029. At the United Nations level, Special Envoy for the Ocean Peter Thomson has called for a 10-year moratorium to give science time to catch up, and the UN’s finance initiative has warned there is no foreseeable way that financing deep-sea mining can be reconciled with sustainable use of the ocean.
Scientists underscore how little is known and how high the stakes are. Marine biologist Diva Amon says the deep sea is “home to incredible life that is fragile, yet essential to the planet,” and warns: “we don’t yet understand what we’re planning to destroy, and once it’s gone, we can’t bring it back.” About 90% of deep-sea species still lack formal names. Removing polymetallic nodules could cause damage on million-year timescales.
Early evidence from trial operations supports these concerns. A study funded by one of the leading mining firms, The Metals Company, found that test mining in the Pacific reduced seafloor abundance and biodiversity by more than a third. The risks go beyond species loss: deep-sea microbes already contribute to medicine — for example, enzymes used in SARS‑CoV‑2 PCR tests and compounds now being explored in cancer trials — and mining could wipe out organisms before they are discovered and studied.
Critics also question so-called green-labelled investment strategies. Tariq Fancy, a former head of sustainable investing at BlackRock, has argued it is often cheaper for firms to “paint yourself green than to actually be green,” and that meaningful change will require political reform and stronger regulation rather than voluntary pledges that leave room for exceptions.
Campaigners say accountability is essential. They call for clearer, consistently applied policies that cover all types of investment, not just project lending, plus public pressure on financiers to align capital with precautionary approaches to deep-sea ecosystems. Without that, they warn, commitments that look strong on paper may still allow capital to flow into ventures that could permanently alter the deep ocean.
Edited by Anke Rasper
(The investigation received a grant from the Investigative Journalism for Europe (IJ4EU) fund.)