Treading water
Water treading is employed when the swimmer wishes to remain in the water without allowing his head to be submerged, yet does not wish to move in any specific direction. Treading water allows him to remain in a relatively fixed position, while using the arms and legs to remain afloat.
Any sort of movement that allows the swimmer to do this can be classified as treading water, but it is more efficient to move the arms and legs in a specific fashion. Two common ways of treading water are kicking extended legs back and forth (see freestyle) and also kicking in an alternating manner, one leg at a time. A refined version of the latter technique, known as "egg-beating" due to the reciprocating motion of the swimmer's legs, is used in the sport of water polo.
See also: List of swimming styles
