Wiktionary
duck dive
n. (context surfing English) the action of duck diving (see verb below). vb. (context surfing English) to push one's surfboard (usually a shortboard) underwater nose-first, to get the surfer and board under a wave that has broken or is just about to break.
Usage examples of "duck dive".
He grabbed a full lung and flipped his leg and lower body above the surface in a duck dive, and went down cleanly into the cold clear water.