The Controversy Over Deep-Sea Mining, Explained

Yves here. While this post gives a useful overview of the political, legal, and ecological issues related to deep-sea mining, I find the focus on the interests of indigenous people to undermine a critique of the plan to exploit these resources. It has the no-doubt-unintended effect of making it seems as if major, and potentially the main opposition comes from a fairly small, economically marginalized interest group that can easily be depicted as inherently retrograde. And let us keep in mind that defenses of traditional lifestyles can be used to advocate for environmentally unfriendly practices, see Japanese whaling as a prime example.

I would have been much happier if the main reservations were instead based on the precautionary principle, with environmental damage from the established technology of deep sea oil rigs (Deepwater Horizon!) presented as cause for pause. Admittedly, the article then discusses multiple possible bad environmental effects, but starting with the concerns of indigenous populations too easily allow for others who object to be dismissed as granolaheads.

By Rachel Ramirez, an independent climate reporter and a fellow with the Metcalf Ocean Nexus Academy who was previously the climate reporter at CNN and has written for Grist, Vox, The Guardian, Rolling Stone, and more. Ramirez is also the cofounder of the Asian American Journalists Association’s Pacific Islander Task Force. Originally published at Yale Climate Connections

or Solomon Pili Kaho’ohalahala, a Native Hawaiian elder known as “Uncle Sol” from the island of Lana’i, the ocean is his lifeline. Over the past few years, he has become the voice of a growing Indigenous movement demanding a moratorium on deep-sea mining, which President Donald Trump has labeled an “urgent matter of national security,” but islanders see as a threat to their home, their food supply, and their way of life.

“We are oceanic people; this is our home,” said Kaho’ohalahala, 75, who like his ancestors grew up as a hunter, gatherer, and fisherman in the Pacific Ocean.

As international regulators scramble to codify the rules, countries like the U.S., Japan, and China are moving to carve up the seafloor’s most mineral-rich areas. More than 40 countries have formally called for a moratorium against deep-sea mining in international waters, with four U.S. states – Hawai’i, Washington, Oregon, and California – already enacting bans.

Kaho’ohalahala has been bringing Indigenous perspectives to the international stage, urging regulators to see the ocean as more than a ledger.

“For them, it’s just a money deal,” he said. “It’s not about the resources, it’s not about people, and it’s not about a vision for the long-term needs of our children yet unborn.”

The rush to mine the ocean floor is being sold as part of a green solution, but for the Pacific, the ecological and cultural costs are staggering. Here’s how the process works and why the controversy is deepening.

What Is Deep-Sea Mining?

Proponents argue that deep-sea mining is a new industrial frontier vital to acquiring the metals needed for the renewable energy transition, along with everything from smartphones to missile systems to artificial intelligence. It involves extracting critical minerals like cobalt and nickel from the deepest parts of the ocean. The latest techniques involve dredging or vacuuming the seafloor using large, robotic equipment.

Commercial mining has yet to begin, but exploration is underway. Tens of thousands of residents from U.S. territories have already signed a petition calling for a moratorium.

How Do Deep-Sea Niners Operate?

Mining the deep seas requires lowering massive machinery into the abyssal plains, as deep as 6,000 meters beneath the waves – the depth of nearly 15 Empire State buildings. These machines scrape, suck, and dredge the seabed to collect mineral deposits, which can be polymetallic sulfides or deposits that form around underwater volcanic openings or mud rich in rare earth elements.

The sought-after deposits are the potato-sized, polymetallic nodules rich in critical minerals like cobalt, copper, nickel, and manganese. Machines then lift the harvest up to a vessel on the ocean’s surface, where collectors separate the nodules from unwanted sediment that is dumped back into the ocean.

Every polymetallic nodule starts as a hard fragment on the ocean floor, like a fossilized shark tooth or a volcanic rock. Over millions of years, dissolved metals – fine bits of manganese, iron, nickel, and cobalt that have washed into the sea from rivers or leaked out of underwater volcanoes – settle and build up on each fragment. It’s such an incredibly slow process that by the time a nodule is the size of a potato, it may be 10 million years old.

Most mining companies have focused their tests on the Clarion-Clipperton Zone, a massive stretch between Hawai’i and Mexico. There, the seabed is practically paved with these nodules.

Who Governs the Ocean?

No single entity rules the world’s oceans. Instead, they are governed by a combination of international law and coastal states.

In 2025, Trump signed an executive order that fast-tracks permits for U.S. companies to explore international waters for deep-sea minerals. Member states of the United Nations Convention on the Law of the Sea – which established the International Seabed Authority, or the U.N. body in charge of regulating the seafloor – blasted the move for bypassing international frameworks. But because the U.S. has never ratified the treaty, it remains a nonmember state.

Despite growing calls for a moratorium, the U.S. continues to fund research expeditions into the deep waters of the Pacific, far beyond exclusive economic zones. Climate activists and other protesters have met these vessels at sea, unfurling banners that say, “Don’t Mine the Moana.”

Even if the U.S. and other governments obey the law of the sea, the treaty only applies in international waters, not to the ocean within a country’s territorial limits.

How Could Deep-Sea Mining Affect Indigenous People?

”As Indigenous people, if we don’t stay on top of these things, we get pushed to the side, and these processes continue,” Kaho’ohalahala said. “So it is important for me to elevate our voices, because we have an inherent responsibility and right to care for our home, which is the ocean.”

Canoeing from island to island on Earth’s largest ocean has always been fundamental to Pacific Islander identity, navigating with the stars, the waves, and the wisdom of sea creatures. During Uncle Sol’s lifetime, rising seas and a changing climate have eroded these ancient traditions. Deep-sea mining poses the latest threat. Stirring up sediment from the seafloor could pollute marine habitats and further damage the delicate and already stressed oceanic web of life.

Aggressive mining clashes with a cultural worldview rooted in reciprocity, said Monaeka Flores, a Chamoru activist and founding member of Prutehi Guåhan, who testified in front of the Guam legislature following a Trump administration announcement expressing interest in mining the seafloor near the American territories of Guam and the Northern Mariana Islands.

When it comes to the ocean, Indigenous people “ask for permission; that when we take, we don’t take too much, we leave some behind,” Flores said. He said that when islanders catch fish, “We put it out to all of our friends, neighbors, and family members,” and islanders also “don’t make loud noise by the ocean.”

“This is a security issue for us as Pacific Islanders, as we are also fighting against climate change,” Flores added.

What Are the Environmental Consequences of Deep-Sea Mining?

Oceanographer Jeff Drazen at the University of Hawai’i at Mānoa is one of the scientists trying to understand the ecological consequences of mineral extraction. Since 2020, he has gone on dozens of research cruises in the Pacific Ocean. His focus goes beyond the seafloor and into the water column above it, where many marine animals live, carbon cycling occurs, and food webs operate. That is where the mining industry plans to dump its waste.

Scientists have a big task. The ocean makes up roughly 70% of the planet, yet the National Oceanic and Atmospheric Administration says that over 80% of the vast ocean floor remains unmapped and unexplored.

Drazen and other scientists are most worried about sediment plumes, vast clouds of ancient silt that can drift for miles and potentially suffocate marine species. They also warn that deep-sea mining could cause water, light, and noise pollution, irreversibly harm unique deep-sea ecosystems, destroy habitats, and reduce biodiversity.

“At shallower depths, we have a pretty good idea of what’s living there, but at greater depths, it’s a total frontier, and it’s going to be affected by mining,” Drazen said.

He and other scientists are still figuring out the depths at which mining discharge should be released into the ocean without widespread consequences.

Despite their research findings, he said, companies are “now moving their discharge depth deeper, but we just don’t know what they’re going to affect, and we’re busy trying to describe what this diversity is.”

Which Species Are Potentially at Risk?

An October 2025 study from Drazen and his team found the habitats of 30 species of sharks, rays, and chimaeras overlap with areas where proposed deep-sea mining may occur. Nearly two-thirds of these species are already threatened with extinction due to human activities like overfishing, so discharge plumes from seabed mining will only further elevate their extinction risk.

The team also found that waste plumes from mining operations threaten critical food sources and could harm the food web. They concluded that mining discharges would affect 53% of all kinds of zooplankton and 60% of types of micronekton, which feed on zooplankton. This problem could ultimately move up the food chain, affecting the shrimp and fish people eat at the dinner tables.

“[The deep sea] is not something we want to mess with,” said Brian Popp, co-author of the latter study and a geologist at the University of Hawai’i at Mānoa. “We need to understand what we’re doing and how we’re impacting those environments.”

But These Metals Are Needed for the Clean Energy Transition, Right?

Companies have framed deep-sea mining as essential to transitioning to clean energy, but critics dismiss this as a form of greenwashing that ignores the immense ecological risks.

“No amount of money is worth this permanent destruction and desecration of this invaluable and irreplaceable resource,” Flores said. “What’s happening is that they’re trying to sell this as a way of giving us clean energy, moving us away from fossil fuel. That is a false solution.”

Drazen noted that fast-evolving battery technology could quickly reduce the perceived need for deep-sea mining. In China, which is the world’s biggest electric car battery manufacturer, batteries no longer include the minerals found in deep-sea nodules like cobalt and nickel.

Opponents argue that rather than opening a new and ecologically fragile frontier, global efforts should focus on improving the human rights and environmental standards of existing land-based mines, where significant deposits remain untapped. Another option is getting serious about recycling the used critical minerals in discarded electronics. They say this would be more energy efficient than mining and will not pollute the ocean.

“Deep-sea mining is not proven necessary to meet critical mineral demand,” Chelsea Muña, director of Guam’s department of agriculture, said in a public hearing. “Recycling and recovery of existing materials presents lower risk alternatives.”

So Why Are Companies Still Rushing to Mine the Sea Floor?

Critical minerals have surged to the top of the global agenda as the cornerstone of economic and national security. China has spent decades securing concentrated control over the critical minerals and rare earths, forcing the U.S., Japan, and the European Union to aggressively fund domestic alternatives to break this strategic chokehold.

The U.S. and Japan, in particular, turned to the ocean. But under the Law of the Sea treaty, international waters and all their resources are the “common heritage of mankind.” Since 2014, member states and the International Seabed Authority, the regulatory U.N. body that oversees mining-related activities in the deep sea beyond national jurisdiction, have been negotiating exploitation regulations for commercial-scale deep-sea mining.

Within a country’s exclusive economic zone, however, the waters and seabed extending up to 200 nautical miles from a nation’s coastline, countries claim special rights and are allowed to do whatever they can with those resources. Japan, for example, has already started exploring and conducting test mining operations within its exclusive economic zones, extracting rare earth mud from the waters near Minamitorishima Island.

>Can I Do Anything to Help Fight Deep-Sea Mining?

In the United States, Indigenous groups are stepping up against deep-sea mining, particularly in U.S. territories. On the islands of Guam and Northern Marianas, groups like Prutehi Guåhan and Friends of the Mariana Trench have been speaking out across social media platforms, submitting public comments to the federal government, and organizing petitions.

Globally, the Deep Sea Conservation Coalition and Greenpeace International have been organizing campaigns around the world calling for a moratorium, including contacting policymakers and holding mining companies to account.