In addition to being surfers’ playthings, waves are the major force sculpting coasts. It doesn’t take monster waves, however. The action of innumerable smaller waves over time can erode rocky coastal promontories or cause entire sand islands to migrate toward the mainland. Waves also drive currents that move sand along shores. Tides cause other daily fluctuations of the shoreline. Overlain on the short-term processes of waves and tides are changes in sea level. The combination of these processes-waves and currents, tides, and sea level change-has produced a variety of features along coasts.