Quick Waterfall Facts Angel Falls, located in Venezuela, is the world's longest waterfall at 3,212 feet (979 meters). It is so long that the water usually turns to mist before it reaches the bottom. Some waterfalls freeze for at least part of the year.

A fascinating and often overlooked fact about waterfalls is that they are constantly "moving" backward (upstream) due to a process called headward erosion. As the immense weight and force of the water crash into the plunge pool at the bottom, it creates "cavitation" and turbulence that erodes the soft rock layers underneath the hard "caprock" at the top. Eventually, the overhanging ledge becomes unstable and collapses, causing the waterfall to recede. For example, Niagara Falls has moved about 7 miles (11 km) upstream over the last 12,500 years. Another surprising fact is that the world's tallest waterfall isn't actually on land; it is the Denmark Strait cataract, an underwater waterfall located between Iceland and Greenland. It is caused by the temperature difference between cold and warm water, creating a "drop" of over 11,500 feet—nearly three times the height of Angel Falls in Venezuela, which remains the tallest waterfall on land.