Rip current

A rip current (or just rip) is a specific type of water current that can occur near beaches where waves break. A rip is a strong, localized, and narrow current of water that moves directly away from the shore, cutting through the lines of breaking waves, like a river flowing out to sea. The force of the current in a rip is strongest and fastest next to the surface of the water.

Rip currents can be hazardous to people in the water. Swimmers who are caught in a rip current and who do not understand what is happening, or who may not have the necessary water skills, may panic, or they may exhaust themselves by trying to swim directly against the flow of water. Because of these factors, rip currents are the leading cause of rescues by lifeguards at beaches.

A rip current is not the same thing as undertow, although that term is used incorrectly when referred to a rip current. Contrary to popular belief, neither rip nor undertow can pull a person down and hold them under the water. A rip simply carries floating objects, including people, out to just beyond the zone of the breaking waves, at which point the current dissipates and releases everything it is carrying.

Causes and occurrence

Rip currents happen when wind and breaking waves push water towards the shore, causing the water level to rise slightly. This extra water then flows back out to sea through the easiest path, often through a deeper area like a gap in sand or rocks. This flow out to sea is what we call a rip current.

These currents can appear along any beach where waves are strong enough, especially where the shore slopes gently or where underwater features like sandbars or reefs create gaps. Rip currents can move very fast close to the surface and might look calm, which can be misleading to swimmers. They often form where there are changes in how waves break, such as near piers, jetties, or areas with different underwater shapes.

Visible characteristics

Rip currents have a special look that can help people spot them before getting in the water. They often appear like a river flowing straight out to sea, especially when viewed from high up. You might notice a flat area where the waves usually break, a foamy "river" moving out to the ocean, or water that looks different in color from the rest.

These signs are important for swimmers and lifeguards to know. In the United States, some beaches have special signs made by the National Oceanic and Atmospheric Administration and United States Lifesaving Association to help people understand rip currents and stay safe. Lifeguards watch for rip currents and will move safety flags to help swimmers avoid them.

Danger to swimmers

Rip currents can be very dangerous for swimmers near beaches where waves break. They are narrow, fast-moving streams of water that pull away from the shore. Most rip currents flow at about 0.5 m/s, but some can be much faster—up to 2.5 m/s, which is too fast for anyone to swim against.

If you ever get caught in a rip current, it’s important to stay calm. Trying to swim directly back to shore can exhaust you. Instead, swim parallel to the shore until you’re out of the current, then return to the beach at an angle. If you can’t escape by swimming, float or tread water and signal for help. Remember, rip currents don’t pull you underwater—they just carry you away from the shore. It’s always best to swim in areas where lifeguards are on duty.

Uses

Experienced water users, such as surfers, body boarders, divers, surf lifesavers, and kayakers, sometimes use rip currents to quickly and easily move out beyond the breaking waves. Rip currents provide a fast and effortless way to get to open water when they need to get past the area where waves are breaking.