The speed at which a human can swim backward can vary depending on individual strength, technique, and swimming experience. In general, swimming backward, also known as backstroke, is slower compared to swimming forward due to factors such as reduced power and visibility.
The average speed of a recreational or beginner swimmer swimming backward is typically slower than their forward swimming speed. It can range anywhere from 1 to 2.5 meters per second (3.6 to 9 kilometers per hour or 2.2 to 5.6 miles per hour).
However, professional or highly skilled swimmers who specialize in backstroke can achieve faster speeds. Elite backstroke swimmers can reach speeds of around 2.5 to 3 meters per second (9 to 11 kilometers per hour or 5.6 to 6.8 miles per hour) or even higher.
It's important to note that these speed ranges are approximate and can vary depending on the individual swimmer's skill, training, and physical abilities.