Waterfalls come in variations: a single sheer drop, a gentler cascade over rapids and others involve a combination of the two like Angel Falls in Venezuela. However, Angel Falls is only the tallest on land. The tallest and largest waterfall in the world by both height and sheer volume of flow is between Greenland and Iceland in the Denmark Strait cataract. It is BELOW sea level. This tampers with the commonly understood meaning of "waterfall" but it is amazing. The Denmark Strait cataract, AKA the North Atlantic Circulation Pump, is on the western side of the Denmark Strait in the Atlantic Ocean. This powerful waterfall drops almost 11,500 feet and carries 175 million cubic feet of water per second. Angel Falls by comparison only drops 3,212 feet and its flow almost evaporates before reaching the ground during summer.

The reason this strange phenomenon of below sea waterfalls exists is due to the variation of the temperatures in the water on either side of the Denmark Strait. Colder water is heavier and drops below warmer water and the eastern side of the strait is a lot colder than the western warmer side. When the the cold and warm waters meet, the cold water sinks rapidly below the warmer water creating a strong downward flow. The flow drops so strongly that it's considered to be a waterfall. There are other areas of the ocean where the same thing occurs but the Denmark Strait is by far the largest. Lakes and rivers are also on the bottom of the oceans.

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