July 1, 2026, 8:30 am | Read time: 3 minutes
The Denmark Strait cataract is the largest and highest underwater waterfall on Earth, with a drop of about 3,500 meters. It lies deep below sea level in the Atlantic Ocean between Greenland and Iceland in the Denmark Strait. But how does an underwater waterfall actually work? TRAVELBOOK explains this fascinating phenomenon.
Waterfalls are among the greatest natural wonders of our planet. They spectacularly plunge into sometimes dizzying depths, impressing and enchanting viewers with their display. However, while many cascades have long been developed for tourism, the highest waterfall on our planet can neither be visited nor observed. And there’s a surprising reason for that. The world’s highest waterfall is actually underwater. It is the so-called Denmark Strait cataract between Greenland and Iceland.
The word cataract derives from the ancient Greek word “katarrhaktēs,” meaning “to plunge down.” Today, the term is synonymous with “waterfall.” In the Denmark Strait cataract, unimaginable volumes of water plunge into the ocean’s depths every second. According to the ” National Ocean Service,” this natural wonder separates the Greenland Sea in the north from the Irminger Sea, part of the North Atlantic, in the south. And it is precisely here that the process occurs, creating the largest waterfall on our planet.
The Water Plunges up to 3,500 Meters Deep
At the point where the Denmark Strait cataract separates the two sea areas, the water plunges over its “edge” to a depth of up to 3,500 meters. For comparison, Angel Falls in Venezuela, the highest waterfall on land, has a height of 978 meters. Thus, the Denmark Strait cataract is more than three times as high as the record holder on solid ground. But how does this astonishing phenomenon actually occur? What causes more than 3.5 million cubic meters of water to pour into the depths every second?
Well, it all has to do with water temperature. In the Denmark Strait cataract, colder water from the Greenland Sea meets warmer water from the Irminger Sea. The colder liquid has a higher density, causing it to sink toward the ocean floor. And in doing so, it plunges over the underwater waterfall, which is essentially a significant elevation of the seabed with a height of up to 3,500 meters. However, this can only be “observed” with scientific instruments, as the water here falls at a speed of just half a meter per second.
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According to ” Live Science,” the Denmark Strait cataract is not only high but also about 480 kilometers wide. It formed during the last ice age over a period of 6,000 years. Water from the Greenland, Icelandic, and Norwegian Seas mixes here with that from the Irminger Sea. The region plays a significant role in water circulation throughout the Atlantic. Incidentally, the Denmark Strait cataract is not the only underwater waterfall on Earth. But it is by far the highest. However, the water here does not plunge more or less vertically into the depths like a cascade on land but rather flows gently down the cataract’s slope.