What causes longshore currents?

Longshore currents are formed from the sudden release of energy as swelling waves break into the shoreline at an angle known as the "angle of wave approach." The direction of motion of these currents is parallel to the beach or coastline.

The velocity of longshore currents as they move along the coast varies in relation to the angle of wave approach, speed and direction of the waves crashing into the beach. Longshore currents that travel at a much faster rate result when high waves break at a sharp angle into steep-sloped beaches. However, when swells with lower wave height approach a gently sloping beach at a wider breaking angle, the speed of longshore currents is significantly reduced.