A rip current, often miscalled a riptide, is a strong, narrow flow of water that moves away from the shore. Rip currents are caused by uneven wave breaks. They form in low spots or gaps between sandbars and near manmade constructions such as jetties and piers. While commonly associated with oceans, rips currents can occur at large lake and sea beaches. In facts, they are the number one natural hazard for beachgoers round the world. Rip currents flow fastest at low tide and are most dangerous in high surf conditions. They can be sudden and unexpected. They drag swimmers out to sea. To escape a rip current, swim parallel to the shore. Swimming into a rip will only lead to exhaustion or, even worse, drowning. Here's how rip currents work. When a wave breaks over a sandbar it dumps water between the bar and the shore. The trapped water flows parallel to the shoreline until it finds a conduit. The channeled water rushes forcefully out to the open water.