The world’s largest waterfall is actually hidden deep underground

Every now and then, you stumble across a fact so strange it feels almost sensationalised – like discovering that the tallest waterfall on Earth is flowing under the ocean’s surface. In fact, the world’s largest waterfall reaches an astonishing 3.5 kilometres in height.

So where exactly is it?

True to its name, the ‘Denmark Strait cataract’ lies hidden beneath the Denmark Strait, the stretch of ocean that separates Iceland from Greenland.

Not only does it plunge to immense depths, but it also spans an incredible 160 kilometres in width. Every second, around 5 million cubic metres of water cascade downward.

But how can a waterfall even exist in the ocean?

The answer lies in a simple but powerful principle of ocean science, as cited by the National Ocean Service: cold water is denser than warm water. In this case, frigid southward-flowing currents from the Nordic Seas collide with the relatively warmer waters of the Irminger Sea.

The Denmark StraitiStock

As the colder water meets the warmer layer, it sinks beneath it, spilling over a vast underwater ridge in the ocean floor. This creates a continuous, downward flow, effectively forming a hidden waterfall.

Because it happens below the ocean’s surface, the Denmark Strait cataract remains completely invisible to the naked eye, detectable only through specialised scientific instruments.

Sadly, even these hidden underwater giants are not immune to the effects of global warming.

In a statement, professor Anna Sanchez-Vidal, said: "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."

You should also read...

• Man scales frozen waterfall in national park amid ‘very rare’ conditions
• The world's largest waterfall is actually underwater

How to join the indy100's free WhatsApp channel

Sign up for our free Indy100 weekly newsletter

Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.