A tumble turn, or flip turn is a technique of turns in swimming, used to reverse the direction in which the person is swimming. It is usually done when the swimmer reaches the end of the swimming pool but still has one or more lengths to swim.
The technique's development is credited, by the International Swimming Hall of Fame, to legendary University of Texas swim coach Tex Robertson while he was training Adolph Kiefer for the 1936 Olympics. [1]
Flip turns are only permitted during front crawl and backstroke races. In butterfly and breaststroke races, regulations require swimmers to touch the end of the pool with both hands simultaneously before turning back for another length.