When a wave reaches the shallow shoreline of an ocean or other large body of water, the upper portion of the wave pitches forward and the wave begins to break—a motion often indicated by crests of foam called whitecaps. The size and forward motion of the wave subsequently diminish. The basic idea behind surfing is to ride the unbroken portion of a wave for as great a distance as possible, using a variety of maneuvers to speed up, slow down, and maneuver around the breaking portion of the wave. Proficient surfers continue to ride until the entire wave has broken and become whitewater.