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Niagara Falls pulls in tourists by the boatload. Angel Falls towers higher than city skyscrapers. Yet both pale in comparison to Earth’s largest waterfall – an enormous, rushing torrent concealed below Arctic waves.

The Denmark Strait cataract drops in slow motion beneath the chilly surface between Iceland and Greenland.

The chute begins thousands of feet down, rolls over a hidden ledge, and keeps sliding for 11,500 feet – more than twice the cruising altitude of a commercial jet.

No roar reaches the surface, no mist fills the air, and passing ships glide on as if nothing remarkable lies below these crucial Arctic waters, which drive Earth’s climate.

The Denmark Strait cataract

Most of Earth’s largest waterfalls form when a river meets a cliff and spills over. Turbulent water gouges the rock, the lip grows steeper, and a postcard scene is born.

Submarine waterfalls follow a different script. Here, colder, saltier water sinks below lighter layers, slipping along the seafloor like syrup down a tilted pan. The motion is silent, pulling entire water masses rather than a single stream.

Oceanographers first confirmed the Denmark Strait cataract decades ago by tracing temperature and salinity profiles through the channel.

Sensors revealed a dense ribbon of Nordic Sea water sliding into the Atlantic basin, gathering speed until it tumbled past a submerged ridge. That ridge acts as the unseen cliff, setting off the tallest plunge on Earth.

Where Arctic chill meets Atlantic warmth

Icy water leaving the Nordic seas is both colder and saltier than the milder Atlantic layer to the south. Density differences created by that contrast drive the flow.

As the dense water reaches the sill between Iceland and Greenland, it spills downward, widening as it falls until the sheet stretches roughly 300 miles – about the driving distance from Chicago to St. Louis.

During the Last Ice Age, roughly 17,500 to 11,500 years ago, glaciers carved trenches across the seabed and left behind the ridge that now serves as the cataract’s tipping point.

Glacial debris, volcanic eruptions, and relentless currents have since hardened the structure, locking a geological funnel in place for the descending water.

Climate change and the largest waterfall

More than 3.2 million cubic meters of water – around 113 million cubic feet – slip over the cataract every second, far outpacing the Amazon River’s flow into the Atlantic.

This slide feeds the lower limb of the Atlantic Meridional Overturning Circulation (AMOC), the global “conveyor belt” that ferries heat, oxygen, and nutrients around the planet.

There is increasing evidence of the effects of global change on the phenomenon of undersea waterfalls.

“A good example is on the Catalan coast, where the decrease in the number of tramontane days in winter in the Gulf of Lion and north of the Catalan coast is causing a weakening of this oceanographic process, which is decisive in regulating the climate and has a great impact on deep ecosystems,” explains marine scientist Anna Sanchez Vidal.

Size of the Denmark Strait cataract

Angel Falls drops 3,212 feet in Venezuela. Niagara clears a modest 167 feet on the U.S.-Canada border. Stack all of Niagara’s water several dozen times, and you still won’t match the cataract’s flow.

Even the Mississippi at flood stage would struggle. Yet the Denmark Strait cataract remains invisible, its roar muffled by more than a half-mile of seawater.

Instruments tell a different story: moored profilers register velocities topping three knots, while sediment cores show layers rearranged by the hidden torrent.

The phenomenon of dense water overflow is particularly intense in the Arctic and Antarctic.

“The poles are the regions where most of the dense water masses – generated by the formation of sea ice at the surface – eventually reach the global ocean floor,” explains David Amblàs of the Department of Earth and Ocean Dynamics at the University of Barcelona.

“The polar areas are like the heart of the oceanic circulatory system: they pump cold, dense water into the great oceanic troughs through the ‘heartbeats’ made by overflows of dense water.”

Much more to learn

The cataract may slow or speed up as Arctic warming alters salinity and temperature patterns. Researchers use autonomous gliders, deep-sea landers, and satellite altimetry to watch for any shift that could ripple through weather systems.

A weakening flow might stall the North Atlantic’s heat pump, cooling Europe and nudging hurricanes onto new tracks.

Yet there is still no direct video of the full descent, and no sensor array captures every eddy. Each expedition peels back only a sliver of the story.

Future projects aim to stitch those slivers together, mapping the plunge in three dimensions and tracking its pulse through the seasons.

Why Earth’s largest waterfall matters

Anyone enjoying mild January weather or a fish fillet pulled from Icelandic waters owes thanks, in part, to the Denmark Strait cataract.

By dragging cold, dense water southward, the cataract clears space for warmer Gulf Stream water to flow north. That exchange tempers winter, nourishes plankton, and steers migratory species toward fertile feeding grounds.

When the torrent quickens, more carbon-rich deep water rises elsewhere, boosting ocean productivity. When it slackens, heat piles up in the tropics, whipping up stronger storms.

In other words, the waterfall no one can see holds a backstage pass to everyday weather and the seafood aisle alike.

From a tourist’s point of view, the cataract offers nothing to watch. From a planetary perspective, it’s a crucial lever, tilting climate and commerce with the quiet push of density-driven flow.

Scientists will keep chasing its rhythm, because the better we know this hidden giant, the better we can forecast the moods of the sea and the sky above it.

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carried out “digital dental surgery” using CT scanning to isolate individual teeth for detailed study

A University of Portsmouth student has discovered a new species of prehistoric mammal dating back 145 million years to the Berriasian age, providing fresh insights into the diversity of early mammals that lived alongside dinosaurs.

Benjamin Weston, 22, an undergraduate paleontology student, made the remarkable discovery while conducting fieldwork in the cliffs of Durlston Bay near Swanage, Dorset. The fossilized lower jaw he found represents a completely new species of multituberculate — an extinct group of early mammals known for the distinctive tubercles on their posterior teeth.

The 16.5mm-long jaw is characterized by a long pointed incisor at the front, followed by a gap and then four razor-sharp premolars. While superficially resembling a rabbit’s jaw, the pointed incisors and distinctive premolars identify it as belonging to the multituberculate group.

This discovery, published in Proceedings of the Geologists’ Association, marks the first multituberculate jaw found at Swanage since Victorian times, and its unique size and shape confirmed it as an entirely new species.

“I instantly had my suspicions of what the jaw was when I found it at the beach, but couldn’t have imagined where the discovery would take me,” said Ben Weston. “I’m extremely grateful to the team and to the university for helping me take my first steps into academic paleontology.”

Dr Roy Smith and Emeritus Professor David Martill, who supervised the research, enlisted the expertise of Dr Steve Sweetman, a former Portsmouth student and now honorary research fellow, who specializes in rare Early Cretaceous mammal fossils from the Isle of Wight and Isle of Purbeck regions.

This was not the first time a student made a once-in-a-lifetime discovery in Dorset. In 2017, undergraduate Grant Smith recovered fossilis of two new species of Humankind’s earliest ancestors from rocks exposed in cliffs near Swanage.

Dr Sweetman said: “This is a remarkable find that reminds me of when Grant found those extraordinary eutherian mammal teeth. When I first saw Grant’s specimens, my jaw dropped — and I had exactly the same reaction to Ben’s multituberculate jaw. It’s incredible that Durlston Bay keeps delivering such significant mammal discoveries by our undergraduate students.”

Advanced technology reveals hidden details

The delicate fossil presented challenges, with pieces of rock obscuring vital details. The University’s advanced CT scanning capabilities proved crucial to the research. Dr Charles Wood, Senior Scientific Officer in the School of Electrical and Mechanical Engineering, used CT scanning to reveal the specimen inside the rock, producing remarkable results due to the contrast between fossil and rock.

The team then collaborated with Jake Keane, a former Portsmouth paleontology student now working in Abu Dhabi (UAE), who processed the CT scans digitally. Within hours, Keane had digitally removed all surrounding rock and performed “digital dental surgery” to isolate individual teeth for detailed study.

Using these digital files, Lead Technician John Fearnly at the University’s 3D printing lab in the Faculty of Technology created replicas magnified ten times, allowing safe study of the precious fossil without risk of damage.

Introducing Novaculadon mirabilis

The new species has been named Novaculadon mirabilis, with “novacula” describing its razor-like back teeth and “mirabilis” referring to the miraculous preservation of the specimen.

Portsmouth paleontology student Hamzah Imran created an artistic reconstruction showing the animal as a small, furry creature with speculative spots and stripes.

The fossil evidence suggests Novaculadon mirabilis was omnivorous, likely feeding on small invertebrates such as worms and insects. The sharp-pointed incisors and ridged, blade-like premolars indicate a feeding strategy distinct from modern rodents like squirrels and rats.

Emeritus Professor Martill reflected on the collaborative nature of the research: “Looking back now that the discovery has been published, I am amazed at how many people it took to describe this little mammal. I especially appreciated that all team members were University staff or present and former students — a true team effort including academics, technicians, alumni, and students with diverse talents across three departments.”

The research demonstrates how early mammals carved out ecological niches while dinosaurs dominated the landscape. Although multituberculates survived the extinction event that killed the dinosaurs, they eventually became extinct around 33 million years ago during the Oligocene period.

Multituberculata represents the most diverse order of Mesozoic mammals, with over 200 known species ranging from mouse-sized to beaver-sized. These mammals occupied various ecological niches over their 130-million-year evolutionary history, from burrow-dwelling to squirrel-like tree climbers.

The discovery adds to Portsmouth’s growing reputation in paleontological research and demonstrates the value of undergraduate fieldwork in advancing scientific knowledge.

The University of Portsmouth’s BSc (Hons) Palaeontology degree offers a uniquely hands-on learning experience, thanks to its location near the Isle of Wight — nicknamed “Dinosaur Island” for its rich fossil heritage. Students benefit from frequent field trips to world-famous fossil sites like the Isle of Wight and the Jurassic Coast, gaining real-world experience that complements classroom learning.

Accredited by The Geological Society of London, the course combines cutting-edge facilities, expert teaching, and a flexible “Connected Degree” structure that allows for paid placements or self-employment years, preparing graduates for careers in science, consultancy, or museum work.