also: ドルフィン・キック
noun
dolphin kick
A swimming kick used in butterfly and underwater phases, where both legs move together in a wave-like motion.
バタフライではドルフィンキックが重要だ。
The dolphin kick is important in butterfly.
彼は水中でドルフィンキックを打って距離
He gained distance underwater by doing dolphin kicks.