The world’s largest waterfall is underwater.

When we think of the world’s mightiest waterfalls, we normally picture them cascading majestically over cliffs to a turbulent plunge pool far below. But the world’s largest waterfall is actually located in the ocean. Known as the Denmark Strait cataract, it flows beneath the Denmark Strait, which separates Iceland and Greenland. At the bottom of that strait, a series of cataracts — beginning some 2,000 feet beneath the surface — plunge to a depth of 10,000 feet, a drop of nearly 2 miles. This underwater waterfall exists due to density differences between the two water masses on either side of the Denmark Strait. When the southward-flowing cold water from the Nordic Seas meets the warmer water from the Irminger Sea, the cold, dense water quickly sinks below the warmer, less dense water, and plunges over a huge drop in the ocean floor. The resulting downward flow is estimated to well exceed 123 million cubic feet per second. By comparison, the discharge of the Amazon River into the Atlantic Ocean is just 7.74 million cubic feet per second.