Butterfly isn't as hard as it looks.It is a fun stroke.It is an exquisite stroke.All its parts fit,and all are necessary.A butterfly swimmer:
1)Must keep his sholders level.
2)Must make all forward movements of the hands and arms above the surface.
3)Must use symmetrical and simultaneous movements of the arms,and of the legs.
4)Must not use a flutter kick or a sidestroke kick.
5)Is permitted to submerge his head.
6)Is not restricted to any particular number of kicks perstroke.