What are longshore currents caused by?

Longshore currents are generated by waves that approach the shore at an angle. When waves break and hit the shoreline, the water travels up the beach at that angle, creating what is known as the swash. When the water recedes back into the ocean, it does so directly perpendicular to the shoreline, forming what is called the backwash. The combination of these two processes results in a net movement of water along the shore, creating longshore currents.

This phenomenon is driven by the interplay of the wave direction and the shoreline's orientation. Consequently, when waves approach at an angle, they lead to the consistent lateral transportation of sand and sediment along the coastline, influencing coastal erosion and the deposition of materials. Understanding this concept is crucial for divers and those involved in marine and coastal activities, as it can affect dive sites and safety.