Deep-sea wildernesses are more important than the promise of seafloor mining

Analysis by Andrew D. Thaler 

SUVA, 15 APRIL 2026 (MONGABAY)—When I set sail on the MV NorSky in the summer of 2008 to probe the depths of Manus Basin off the coast of Papua New Guinea, I believed in the promise of deep-sea mining. As an early-career deep-sea ecologist, I was swayed by arguments in favor of this emerging industry. It offered a new way to obtain the metals needed for the renewable energy revolution, one allegedly free of the human rights and environmental abuses of terrestrial mining. The company was Nautilus Minerals, and the plan was to mine an active hydrothermal vent field called Solwara I. 

What is a hydrothermal vent and why would anyone want to mine one? When seawater is drawn down into the earth and heated under enormous pressure, it rises through cracks in the crust, erupting from the seafloor in metal-rich plumes. Those metals are deposited on the walls of a growing chimney. Deep-sea miners call this structure a seafloor massive sulfide. They can be rich in gold and silver, as well as copper, zinc, lead and rare earth elements. 

By most estimates, Solwara I is among the most valuable seafloor massive sulfides ever discovered. And it is not only rich in metals, it is rich with life. 

The communities that grow around hydrothermal vents depend on the chemical energy of the vent plume. The geological process that deposits metals also supports ecosystems found nowhere else in the ocean. These vent fields are rare: the total area of all known hydrothermal vent fields is smaller than the island of Manhattan. 

Understanding how these rare communities are connected across oceans is critical to understanding how mining could reshape the deep sea. Which is how I found myself aboard this ship, on an expedition to study the biodiversity and connectivity of hydrothermal vent communities at Solwara I. 

Hydrothermal vents can be ephemeral. They turn over to a decadal rhythm, with old vents shutting down and new vents opening as the geological forces driving their formation fluctuate. For Nautilus, the dynamic nature of these vents presented an opportunity. Unusual for a hydrothermal vent field, Solwara I lies immediately beneath an active submerged volcano. The natural dynamics of the site present the possibility that the ecosystems it supports could be resilient to mining impacts. Solwara I already experiences natural disturbance. Perhaps it could endure a little unnatural disturbance, too? 

It wasn’t a bad hypothesis, but it needed to be tested. 

The first thing you see as you approach the towering edifices of Solwara I are squat lobsters, small crustaceans of the genus Munidopsis that look like hermit crabs pulled from their shells. Startled by the lights and noise of our remotely operated vehicle (ROV), the underwater robot we use to study the deep sea, they would launch themselves into the water column. Legs and claws spread wide, they’d drift back to the seafloor. 

Only then do you see the vent plumes, great billowing black clouds. Surrounding these plumes are swarms of pale, eyeless shrimp of the genus Chorocaris. The ROV’s lights reflect off a glittering spot on their carapaces, a sensory organ like an eyespot that senses the black-body radiation (thermal electromagnetic radiation) emitted from the vent. These shrimp can “see” the heat of the hydrothermal plume, allowing them to swim close enough to feed, but not so close to boil. 

You are guided to the mouth of the vent chimney by a bull’s-eye of biodiversity. Two fist-sized snails dominate the vents of Solwara I: a ghostly white snail with a paper-thin shell covered in long, stiff hairs from the genus Alviniconcha, and an abyss-black snail with a thick, heavy shell, from the genus Ifremeria. Alviniconcha prefers the warm waters immediately around the vent outflow, while Ifremeria likes its home a little cooler. Together, they create concentric rings of snails that encircle the vent. 

Closer still, scale worms crawl through crevices. Mussels crowd around small cracks where cooler vent plumes emerge from the seafloor. Limpets cling to the shells of Ifremeria, but avoid the bristles of Alviniconcha. Crabs scuttle across mounds of snails. Octopuses and eelpout fish wind through rocky outcroppings. In the sediment, at the base of the chimney, a predatory snail from the genus Eosipho lies in wait for a hapless Alviniconcha or Ifremeria to fall from their perch at the top of the chimney. 

Even around the periphery, and among the so-called inactive areas, where hydrothermal venting has slowed or stopped, strange communities form. Predatory glass sponges that look like lollipops hunt for copepods that drift through their domain. Cold-water corals sprout from rocky outcrops, brittle stars wrapped around them. An octopus broods her eggs. A chimera, a cartilaginous fish in the order Chimaeriformes, drifts slowly past the ROV. 

What I learned studying the communities that thrive around Solwara I, as well as hydrothermal vents across the Western Pacific, is that, though these ecosystems are dynamic, they are also deeply interconnected. Those connections are fragile. The impacts from mining would be catastrophic to the communities at Solwara I, and the knock-on effects would threaten surrounding ecosystems. 

There is a curious paradox in the deep sea: while most of the seafloor is characterized by exceptional biodiversity and extremely low biomass (there are lots of species, but few individuals of those species), hydrothermal vents tend towards the opposite. Biomass is high. Biodiversity is low. 

Not so at Solwara I, which hosts both incredible biodiversity and tremendous biomass. Of all the vent ecosystems in the ocean, the hydrothermal vents of the Western Pacific, including Solwara I, are the most biodiverse. 

Faith displaced 

I entered this project in good faith, working with the mining company to help determine whether or not deep-sea mining at Solwara I could be conducted with minimal harm to the marine environment. I exited convinced that there is no viable path forward for hydrothermal vent mining, anywhere in the ocean. Solwara I may present the best-case scenario for mining a hydrothermal vent, but the best-case scenario is not good enough. Nautilus Minerals thought otherwise, and they applied for the world’s first commercial deep-sea mining permit. 

Nautilus Minerals received a commercial permit to mine Solwara I from the government of Papua New Guinea in 2011. Despite clearing the last regulatory hurdle, they were never able to start mining. Unable to secure a ship and reeling from several blows to their business, the company went bankrupt in 2019, its assets auctioned off, its three massive mining robots rusting away in Port Moresby. That same year, in response to both growing pressure across the Pacific and increasing local resistance to the Solwara I project, Papua New Guinea instituted a 10-year moratorium on deep-sea mining within its waters. 

Today, the deep ocean off the coasts of Alaska, American Samoa, and the Northern Mariana Islands face a renewed threat from deep-sea mining. Though an early pioneer, the United States has long sat on the sidelines of this developing industry. 

Now, under directives from the Trump administration, the Bureau of Ocean Energy Management (BOEM) and the National Oceanic and Atmospheric Administration have begun the process of permitting mining across vast regions of the deep seafloor in both U.S. waters and the high seas, beyond any nation’s borders. While most presume that polymetallic nodules, metal-rich cobblestones scattered across the abyssal plain, are the prime target for this new push to mine the deep, the permitting process under consideration and the executive order that kick-started this process include not just nodules, but hydrothermal vents and metal-rich crusts on seamounts. 

Just this month, BOEM released its recommendations for leasing areas of the seabed around the Mariana Trench, doubling the size of the initial proposed area and adding 33 million acres (more than 13 million hectares) of seafloor, on which the only potential significant mineral deposits are locked in hydrothermal vent sulfides. 

Polymetallic nodule mining promises access to the abundant mineral resources of the abyssal plain, including cobalt, nickel and manganese, with a lighter touch than hydrothermal vent or seamount mining. But nodule mining is not without its own environmental risks. 

The nodules are habitat, and removing them from the seafloor threatens the animals that depend on them. The sediment plumes produced by mining tools can spread throughout the water column, threatening seafloor ecosystems as well as commercially important fisheries. With significant research and technological advances, those potential impacts may yet be overcome, but nodule mining is not ready, yet. 

There’s an argument that permitting is the only thing holding back deep-sea mining, that with the renewed push from the Trump administration to develop the industry through an expedited permitting process, deep-sea mining is inevitable. 

Deep-sea mining is a wickedly challenging endeavor. At full scale, commercial deep-sea mining will be among the most logistically complex offshore operations ever undertaken, with robotic technologies as yet unproven. An expedited permit is no guarantee of success: even in the best-case scenario, with a commercial license in hand and mining tools waiting at the dock, Nautilus Minerals failed. 

The deep sea does not offer guarantees, except for this: near limitless potential for discovery. 

We have barely begun to explore the deepest places on our planet. Less than a tenth of a percent of the deep seafloor has ever been observed. As researchers, explorers and even miners increase our presence in the deep ocean, we will discover new animals, ecosystems and ecological processes. Some, like hydrothermal vent communities, will be so unlike anything seen before that we lack the necessary biological framework to predict their existence. 

We’ve found octopuses brooding their offspring and skates laying their eggs in the warm waters of diffuse flow vents, for instance. At a long-inactive hydrothermal vent field, scientists discovered more than 30 new species of snail in communities that endure by living off traces of chemical energy that persist long after the vent stops. In the Indian Ocean, we found another surprising snail, this time with a shell made from iron. When brought to the surface and exposed to air, it begins to rust. 

Hydrothermal vent mining has largely — but not entirely — fallen out of favor with the principal companies pushing for the rapid development of the deep-sea mining industry, but this potential for discovery is not limited to seafloor massive sulfides. 

In a hadal trench, Chinese scientists uncovered a hitherto undiscovered ecosystem, the deepest animal habitat ever observed. In Pacific nodule fields, researchers delighted in the discovery of a whiplash squid that hides among the cobblestones, waiting to ambush its prey. On ferromanganese crusts on the Rio Grande Rise, Brazilian scientists found vibrant communities built atop cold-water coral reefs. On the Blake Plateau, at the site of the very first experimental deep-sea nodule mine from the early 1970s, U.S. researchers documented a coral reef larger than the state of Vermont. It is the largest cold-water coral reef in the world and it wasn’t discovered until half a century after it was almost dredged by a deep-sea miner. This near miss on the Blake Plateau highlights just how easy it is for enormous ecosystems to go unseen in the deep, even in areas being explored for deep-sea mining. 

How will deep-sea mining operations respond to the discovery of something truly novel on the seafloor? Within the first two to three years of a full-scale commercial deep-sea mining operation, we will nearly double the amount of time humans have spent observing the deep seafloor. Within the 30-year operational life of a polymetallic nodule mine, the likelihood of discovery is guaranteed, and not just new species of nematodes or interesting snails, but whole ecosystems and ecological processes, with the potential to fundamentally change our understanding of life on Earth. 

A discovery on the scale of hydrothermal vent communities or cold-water coral reefs would mandate an operational full stop, a complete overhaul of any environmental management plan, and years, if not decades, of focused study. When deep-sea mining companies are the only ones with the resources and capacity to monitor these sites, how do we safeguard this potential for discovery? 

Discovery is inevitable. The tragedy before us now lies in rushing to exploit the deep sea before we understand what we could lose…..PACNEWS 

Andrew D. Thaler is a deep-sea ecologist, conservation technologist and ocean educator. He is also a Public Voices Fellow on Technology in the Public Interest with The OpEd Project.