Butterfly is a difficult stroke to swim as it needs both stamina and style. The movements you need to make, however, are not difficult because you will have done many of them before in other strokes.

For jobs on the special operations/special warfare side (SEAL, SWCC, diver/EOD), you must swim a stroke that is considered an underwater recovery stroke, such as the breaststroke, elementary side ...

Mark Spitz nearly mastered swimming's most difficult stroke, the butterfly. Fulfilling all the pre-Olympic hype, he won four individual events -- in the 100- and 200-meter freestyle and 100- and ...