Scientists make an incredible discovery 10 kilometers beneath the ocean.

Far below the last rays of sunlight, where pressure can crush steel, a hidden landscape has revealed a startling secret.

Researchers working in one of the deepest trenches on Earth say they have found a thriving ecosystem nearly 10 kilometers down, in a place long thought too hostile for complex life. Their observations, made with a crewed submersible and supported by detailed chemical analyses, reshape what we thought we knew about the deep ocean.

A Hidden World at the Bottom of the Hadal Zone

The Kuril Trench, north of Japan and stretching toward the Aleutian Islands, drops to depths beyond 10,000 meters. Oceanographers call this part of the planet the hadal zone-a reference to Hades, the underworld. Here, sunlight never reaches, temperatures hover just above freezing, and pressure climbs to more than a thousand times what it is at sea level.

For decades, scientists assumed that only scattered scavengers could survive under such conditions. In 2024, a series of dives using the Chinese crewed submersible Fendouzhe began to challenge that view. During descents to around 9,500–10,000 meters in the Kuril Trench, the team filmed something far more organized than a few isolated animals drifting over mud.

Instead of a barren seafloor, high-definition cameras revealed dense patches of life: thickets of tube worms, clusters of clams, and streams of tiny crustaceans weaving between them.

These animal communities sit on dark, fine sediments pierced by shimmering fluid seeps. The water around them looks ordinary at first glance, but chemical sensors tell a different story: it contains high concentrations of methane and hydrogen sulfide rising from the underlying rocks.

Life Without Sunlight, Powered by Chemistry

Because light never reaches these depths, photosynthesis cannot power the food web. Instead, microbes and animals rely on a different energy source: chemical reactions between seawater and the gases seeping from the trench floor.

Microbial communities in the sediments and inside animal tissues use methane and sulfur compounds to drive a process known as chemosynthesis-more specifically here, chemolithoautotrophy. Rather than capturing light, they harvest energy from the oxidation or reduction of chemical compounds, then use that energy to build organic molecules.

In this system, bacteria play the role that plants and algae play at the surface: they form the base of the food chain, turning raw chemistry into biomass.

The animals filmed in the trench appear finely adapted to this chemical engine:

• Long, red-plumed tube worms, likely siboglinids, lack a functioning gut and instead house symbiotic bacteria in their internal tissues.
• Bivalves cluster around seep outlets, with gills packed with microbes that process methane and sulfides.
• Amphipods and other crustaceans move in constant swarms, grazing on bacterial mats and organic particles.
• Sea cucumbers (holothurians) sift sediment, recycling material that sinks from above or is produced by microbes.

According to the research team, this setup resembles known seep and vent systems at shallower depths, but the Kuril communities sit far deeper than most previously recorded ecosystems of this kind. Some patches may extend for more than 2,500 kilometers along the trench, forming a vast, discontinuous network of chemically fueled habitats.

The Trench as a Geological Life-Support Machine

The Kuril Trench exists because the Pacific tectonic plate dives beneath the smaller Okhotsk plate. As the oceanic crust bends and descends, it fractures, warms, and dehydrates. Fluids enriched in methane and other gases rise through faults and cracks, eventually leaking into the overlying sediments.

Scientists aboard the research vessel sampled both water and mud near the seeps. Lab measurements indicate that the methane is produced mainly by microbes within the sediments, not only by deep geological processes. Microorganisms reduce dissolved carbon dioxide using hydrogen to form methane. That methane then feeds a second group of microbes that oxidize it and build new biomass.

This two-step microbial loop, rooted in geochemistry, supports the entire ecosystem. It shows how geology and biology remain tightly linked even at the deepest points of Earth’s oceans.

The trench is not a silent scar on the seafloor. It acts more like a slow, pressurized bioreactor, where rock, fluid, and life constantly interact.

Creatures Shaped by Crushing Pressure

Life at nearly 10,000 meters faces physical stresses that would destroy ordinary cells and tissues. Proteins can lose their structure, membranes may become rigid or leaky, and gas-filled spaces collapse. Yet the animals and microbes here appear not only to survive, but to thrive.

Researchers suspect several adaptations:

• Specialized molecules called piezolytes help stabilize proteins under extreme pressure.
• Cell membranes contain unusual fatty acids that stay flexible in cold, dark conditions.
• Many animals lack gas-filled cavities and instead rely on gel-like tissues or high internal salt concentrations to maintain buoyancy and structure.
• Symbiosis reduces the need for energy-intensive digestion, replacing it with direct chemical exchange between host and bacteria.

Because these traits take millions of years to evolve, the communities on the trench floor may represent lineages that have tracked deep-sea conditions across long geological spans. Their survival adds another piece to the puzzle of how far life can adapt under extreme pressure.

Redrawing the Limits of Where Life Can Exist

This intense, self-sustaining ecosystem-thriving without sunlight at near-record depths-changes how scientists think about habitability. For a long time, discussions of the “limits of life” focused on temperature, salinity, or acidity. Pressure often seemed like a more absolute barrier.

The Kuril observations show that, given the right chemistry and enough time, complex communities can form even under enormous loads of water. That has direct implications for astrobiology. If microbes and animals can manage this on Earth, simpler microbial ecosystems might exist in other dark oceans in the Solar System.

Environment	Main energy source	Potential for similar ecosystems
Kuril Trench (Earth)	Methane- and sulfide-driven chemosynthesis	Confirmed complex community
Subsurface Mars	Rock-water reactions, possible hydrogen	Hypothetical microbial habitats
Europa (moon of Jupiter)	Seafloor hydrothermal activity beneath ice	Strong candidate for chemosynthetic life
Enceladus (moon of Saturn)	Alkaline hydrothermal vents in a deep ocean	Supported by plume chemistry data

By studying these trench ecosystems, researchers hope to refine which chemical signatures could indicate life in data from future Mars drilling missions, landers on icy moons, or orbiters sampling plumes.

Deep-Sea Mining and the Risk to Unseen Ecosystems

While the Kuril discovery expands the search for life beyond Earth, it also sharpens the stakes of decisions being made by companies and international regulators. Several countries and firms are pushing for large-scale mining of deep-sea minerals: cobalt-rich crusts, manganese nodules, rare earth elements, and more. Many targeted areas lie on abyssal plains and seamounts that scientists have barely surveyed.

Finding a dense, specialized ecosystem at nearly 10 kilometers depth sends a clear signal: the deep ocean still hides entire biological systems we barely understand-let alone protect.

Mechanical disruption from mining vehicles, sediment plumes, noise, and chemical contamination could affect not only visible animals but also the microbial networks that power hadal life. Because these communities grow slowly and depend on stable chemical flows, damage could persist for centuries or longer.

Some researchers now argue that environmental baselines for deep-sea projects should include systematic searches for methane seeps and other chemosynthetic hotspots. Without that, regulations may overlook places where disturbance would destroy rare, fragile habitats.

What These Trenches Tell Us About Earth’s Past and Future

These findings also feed into debates about where life first emerged on Earth. One hypothesis places life’s origin near hydrothermal systems on the early seafloor, where steep chemical gradients provided a steady, usable energy source. The Kuril communities show that similar principles still operate today-at a different scale and in different structures.

By analyzing the genomes of trench microbes and animals, scientists hope to trace which biochemical pathways link modern chemosynthetic life to ancient ancestors. That work could clarify whether early life began in alkaline vents, in shallower hot springs, or across multiple sites that later merged into a single global biosphere.

For the public, ecosystems thriving 10 kilometers down can feel abstract. One way to visualize it is to imagine a high-rise building stacked from sea level to the trench floor. Every 1,000 meters adds another “floor” of pressure and darkness. At the bottom, against all expectations, you find a bustling city running not on electricity but on slow chemical combustion-with bacteria as power plants and tube worms as apartment towers.

That mental model also reframes other activities. When scientists discuss carbon storage under the seafloor, geoengineering, or subsea infrastructure, the Kuril findings are a reminder that these deep layers are not empty. They host complex interactions among rock, fluid, and life that help stabilize Earth’s chemistry over long timescales.

The hadal trenches-once treated as remote dumping grounds or mere geological curiosities-now look more like laboratories nature has been running for millions of years. Studying them closely may reshape mining policy and astrobiology plans, and it may also deepen our understanding of resilience, adaptation, and the quiet ways life persists where no one expected it.