Pushing your board under a breaking wave to pass beneath it instead of being thrown back.
Without a duck dive you simply won't reach the line-up on a decent day — you paddle for ten minutes and end up back on the beach. The sequence: paddle hard, then just before the wave put both hands on the rails at chest level, extend your arms and drive the nose steeply down, then push the tail under with a knee or foot so the whole board submerges. Underwater you go long and let buoyancy carry you up behind the wave. Important: it only works with a board you can push under — on a longboard it doesn't, and you use the turtle roll instead, flipping over with the board underneath you.