Timing is everything

With crashing waves, it’s best to wait until the waves have broken on the rocks and are starting to suck back over them before taking your shot. This results in greater contrast between the white water and the black rocks, and produces lots of miniature waterfalls that add interest (see Hot Shot #4 above). This can be done using your camera’s self-timer mode, but it’s tricky to anticipate when the waves will be at their optimum position, so a remote release is a better bet.