There are more mountains under the ocean than on all continents combined

Introduction: a mountain range hidden beneath kilometers of water

A hundred thousand peaks no one has ever seen

When people think of the planet's greatest mountain ranges, the Himalayas, the Andes, or the Rockies immediately come to mind. Yet the vast majority of the planet's peaks are not found on the continents we walk on every day, but lie hidden beneath kilometers of water, in the total darkness of the ocean floor. Scientists estimate there are more than 100,000 seamounts taller than 1,000 meters scattered across the world's oceans, a figure that far exceeds the total number of mountains recorded across every continent combined.

This finding, as simple as it is staggering, shows just how deeply our perception of planetary geography remains skewed by our land-based experience, shaped by centuries spent measuring the world from dry ground rather than from the seafloor. We have been drawing maps of the world for centuries, and yet most of our own planet's relief remains completely invisible to us, swallowed beneath the ocean.

Most peaks have never been explored in detail

What makes this figure even more striking is that the vast majority of these seamounts have never been mapped in detail, nor directly explored by submersibles or autonomous vehicles. Unlike land mountains, which can be photographed, climbed, or flown over, these submerged formations remain largely beyond the reach of direct human observation, known mainly through indirect bathymetric surveys carried out from the surface.

This reality places the exploration of seamounts among the great scientific undertakings of the twenty-first century, comparable in ambition to space exploration, but focused on the depths of our own planet rather than on distant worlds. It is a reminder that some of the biggest blank spots on the map are not light-years away, but just a few kilometers beneath the waves.

How these sunken giants are born

Underwater volcanism, the engine behind these formations

The vast majority of seamounts form through volcanic activity, the result of lava gradually accumulating from hotspots or fracture zones on the ocean floor. Some of these volcanic structures can reach heights comparable to the greatest mountains on land, rising several thousand meters from the ocean floor without ever breaking the surface of the water.

Other seamounts result from more complex tectonic processes, tied to plate movement and the gradual deformation of oceanic crust over millions of years. This geological diversity explains why seamounts display extremely varied shapes, sizes, and compositions from one ocean region to another.

Structures that evolve on geological timescales

A seamount never forms in an instant: its growth stretches over periods measured in hundreds of thousands, even millions of years. Some of these formations are still active, fed by persistent volcanic hotspots, while others have long gone dormant, frozen remnants of past geological activity. There is something fascinating about imagining these mountains growing, silently, in total darkness, never once receiving a ray of sunlight.

This geological slowness contrasts sharply with the speed of our modern mapping technologies, which can now detect in a matter of hours structures that took millions of years to form beneath the ocean surface.

Isolated biological oases in the deep ocean

Rich ecosystems concentrated around the slopes

Far from being simple, lifeless geological formations, seamounts play a considerable ecological role. Their steep slopes disrupt deep ocean currents, forcing nutrients to rise from deep layers toward zones closer to the surface, a phenomenon known as upwelling. This dynamic draws an exceptional concentration of marine life, turning each seamount into a true biological oasis amid the relatively nutrient-poor vastness of the surrounding deep ocean.

Cold-water corals, giant sponges, schools of fish, and a wide range of invertebrates often gather in remarkably high densities around these structures, creating unique ecosystems that marine biologists consider biodiversity hotspots comparable to the richest tropical coral reefs.

Worlds isolated from one another

A particularly intriguing aspect of seamounts lies in their relative isolation. Separated by hundreds, even thousands of kilometers of inhospitable deep ocean, these formations can host populations of species that have evolved somewhat independently, much like terrestrial islands that foster the emergence of unique endemic species. This dynamic makes each seamount a natural laboratory of evolution, potentially home to a specific biodiversity still largely unknown to science.

This biological isolation means every new seamount exploration could potentially reveal new species, almost as if every submerged peak were its own lost island, inaccessible except to scientific teams equipped with advanced underwater technology.

Mapping the unmappable: the Seabed 2030 challenge

An international program of unprecedented scale

Given the scale of the work still to be done, an international program called Seabed 2030 has set itself the goal of mapping the entire ocean floor of the planet by the end of the decade. This initiative, which brings together government agencies, scientific institutes, and private partners from around the world, is one of the most ambitious mapping projects ever undertaken on a global scale.

The work of Seabed 2030 relies notably on data provided by organizations such as NOAA and GEBCO, the General Bathymetric Chart of the Oceans, which has compiled depth measurements collected by ships and scientific instruments worldwide for decades.

Increasingly precise sonar technology

Modern mapping of seamounts relies primarily on multibeam sonar technology, capable of emitting acoustic waves that bounce off the ocean floor and allow researchers to reconstruct, with growing precision, the exact relief of the ocean depths. This equipment, installed aboard specialized oceanographic research vessels, has considerably improved the resolution of available bathymetric maps over the past two decades.

Despite these technological advances, the pace of mapping remains limited by the number of available ships and the high cost of these campaigns, which explains why a significant share of the planet's seamounts remains, to this day, largely unknown to cartographers. Chartering a single research vessel for weeks at a time is expensive, and many of the most remote ocean regions see very little scientific traffic in a given year.

Why this missing knowledge really matters

Stakes for navigation and maritime safety

Beyond purely scientific interest, precise mapping of seamounts carries considerable practical importance for maritime navigation safety. Poorly mapped underwater formations can pose a hazard for certain types of navigation, notably for submarines and underwater equipment operating at intermediate depths, far from direct satellite monitoring.

This security dimension adds to the already considerable ecological and scientific stakes, further reinforcing the case for a sustained international effort toward complete mapping of the ocean floor, an undertaking that would benefit both fundamental research and practical human activities at sea, from commercial shipping to laying underwater cables that carry much of the world's internet traffic across ocean basins.

A reservoir of scientific discoveries to come

Every newly and thoroughly mapped seamount represents an opportunity for scientific discovery. Marine biologists expect the systematic exploration of these formations to keep revealing, in the years ahead, new animal and plant species, along with valuable information about the geological processes that have been shaping our planet's oceanic crust for millions of years.

There is something intoxicating about the thought that the next great scientific discovery might not come from a distant exoplanet, but from a sunken peak a few hundred kilometers from our coastlines, never yet explored by human eyes.

Understanding currents through underwater relief

Seamounts are not simple isolated geological curiosities: they directly influence the circulation of deep ocean currents, creating obstacles that deflect or accelerate moving water masses. This influence on overall ocean circulation has direct repercussions for the distribution of heat across the planet, a key factor in understanding the mechanisms of global climate.

Modern climate models now incorporate increasingly precise bathymetric data to refine their forecasts, which is why agencies like NOAA consider seafloor mapping an issue that goes well beyond simple geographic curiosity, touching directly on our understanding of global climate change.

A constantly expanding database

Every measurement campaign carried out under Seabed 2030 enriches a global database accessible to researchers from every country, fostering unprecedented international scientific collaboration in this field. This collaborative approach considerably accelerates the pace of discovery, with each new national contribution helping to fill in a little more of the vast blank spaces that still remain on the world's bathymetric maps.

From climate data to jaw-dropping examples

Peaks taller than some land mountain ranges

Some seamounts rival iconic land mountains in height. Measured from their base on the ocean floor to their summit, several exceed 4,000 meters in elevation, a height comparable to famous alpine peaks, with the key difference that their summit remains submerged beneath hundreds, even thousands, of additional meters of water before reaching the ocean's surface.

This dizzying scale is a reminder that the planet's most spectacular relief is not necessarily found where we imagine it to be. The highest point measured from base to summit, if underwater structures are included, is not necessarily located on a continent, which considerably upends traditional rankings based solely on altitude above sea level.

Entire ranges still without a name

Beyond isolated peaks, some ocean regions are home to true seamount chains, stretching across hundreds of kilometers, often the result of a tectonic plate drifting over a fixed volcanic hotspot. Many of these chains remain partially unnamed, for lack of sufficiently systematic exploration, a situation that contrasts sharply with the cartographic precision that continental mountain ranges have enjoyed for centuries.

It's hard not to find something poetic in the idea that entire mountain ranges, as large as some famous massifs, are still waiting somewhere beneath the ocean to be given a name.

Conclusion: a planetary relief still largely waiting to be discovered

A map of the world waiting to be rewritten

With more than 100,000 seamounts recorded, and likely many more still undetected, our planet holds a mountainous relief whose greater part remains invisible to human eyes. This reality upends our usual conception of terrestrial geography, centered almost exclusively on the landforms we can directly observe from the surface of the continents.

The patient work carried out by programs like Seabed 2030, in collaboration with agencies such as NOAA and GEBCO, promises to gradually redraw our understanding of planetary relief as a whole, revealing, year after year, new peaks that were until now completely unknown.

An invitation to look at the ocean differently

The next time you gaze out at the sea horizon from a beach or the deck of a boat, remember that beneath that seemingly flat and uniform expanse lies a mountainous landscape of unsuspected richness, with its own peaks, its own valleys, and its own biodiversity oases. The ocean is not just a surface: it is an entire continent of hidden relief, waiting to be explored and understood in the full complexity of its geology and biology. Somewhere out there, an unnamed peak taller than many famous mountains is still sitting in total darkness, simply waiting for someone to notice it exists.

By Maxime Marquette, columnist

Sources

Primary sources

Seabed 2030 — International program for complete ocean floor mapping — 2026

NOAA — Data and research on seamounts and bathymetry — 2026

GEBCO — General Bathymetric Chart of the Oceans — 2026

Secondary sources

National Geographic France — Environment and ocean exploration — 2026

Futura Sciences — News and features on planetary science — 2026

Sciences et Avenir — Science news — 2026