Thats right Nick... the reason a wave "breaks" is primarily because of "drag" on the ocean floor. The shallower the water, the quicker the wave will break. The deeper the water, the longer the wave can run without breaking until it hits shallower water - as the bottom water contacts the floor, the friction slows the bottom of the wave down, causing the top of the wave to fall. So generally speaking, white water means shallower, clear blue means deeper. Often, as in the picture that Nick shows, there is a sandbank far out, then a hole/gully, then another sandbank. In these deeper gullies, the predators often lurk, waiting for the bait fish that feed in the banks of the gullies.
... make sense??