Underwater waterfall

The Denmark Strait cataract, also called the North Atlantic Circulation Pump or the Greenland Pump, is an underwater waterfall found on the western side of the Denmark Strait in the Atlantic Ocean. It is the world's highest underwater waterfall, with water falling almost 3,505 metres (11,500 feet).

It is formed by the temperature differential between the water masses either side of the Denmark Strait, the eastern side being much colder than the western. Due to the different densities in the masses caused by this temperature difference, when the two masses meet along the top ridge of the strait, the colder, denser water flows downwards and underneath the warmer, lighter water, thus creating a downward flow of water, or waterfall.

It is thought that the Denmark Strait cataract has a flow rate exceeding 175 million cubic feet (5.0 million cubic meters) per second, making it 350 times as voluminous as the extinct Guaíra Falls on the border of Brazil and Paraguay, which was once thought to be the most voluminous waterfall on Earth, which was 12 times more voluminous than Victoria Falls.