Undertow (water waves)
= Undertow (water waves)
{wiki=Undertow_(water_waves)}
Undertow refers to the strong water currents that occur beneath the surface of waves as they break on the shore. When waves crash onto a beach, they can create a flow of water that moves back toward the ocean. This flow is often strongest just below the surface and can pull sand and debris with it, creating a current that can be hazardous for swimmers.