Wiktionary
n. A swimming action resembling the leg part of the breaststroke, sometimes used to avoid disturbing sediment which can obscure vision in the water.
WordNet
n. a swimming kick; knees are drawn upward and outward so the legs can be brought together when fully extended
Wikipedia
The frog kick is an underwater propulsion kick used by scuba divers, particularly cave divers, wreck divers, and those who practice the Doing It Right philosophy. It is similar to the swimming action of a frog or the leg action in the breaststroke.
Usage examples of "frog kick".
Then I pulled out the head and continued on by means of the frog kick and underbody sculling with my right hand.
He propelled himself using his legs beneath the water in a strong frog kick so that no sound could be carried in the night.
Every time Johann made a frog kick, the pain in his knee increased.
He swam just beneath the surface, arms extended, thrusting ahead with a powerful frog kick.