It’s the underwater waterfall in the Denmark Strait.
Colder and warmer currents going in opposite directions meet at this straight, causing the colder, denser water to sink beneath the warmer one. When this happens at a place where there’s a drop in the ocean floor, the water is pushed at incredible speeds down, creating a waterfall.
At the Denmark Strait cataract, water drops from 2,000 feet to 10,000 feet below the surface. The waterfall is around 11,500 feet (3,505.2 meters) high. This is much taller than the tallest waterfall on land, Angel Falls, which measures 3,212 feet (979 meters).