If the wind is blowing steadily toward the shore, the risk of rip currents increases, but other factors and features can also make rip currents more likely to occur. They are not always easy to spot, so it is said that these are the hidden dangers of the beaches.
It is often believed that rip currents pull you underwater, but this is a misconception. Rip currents are fast-moving channels that can drag a swimmer away from shore and exhaust them as they try to fight their way back to safety. This is what often results in deaths. The National Ocean Service estimates thousands of people are rescued from rip currents each year in the U.S. The United States Lifesaving Association estimates that the annual number of deaths due to rip currents on our nation's beaches exceeds 100. Rip currents account for over 80% of rescues performed by surf beach lifeguards. Rip currents are the leading cause of surf-related deaths.
Why do they form?
Rip currents are caused by uneven wave breaking along coastlines, including oceans, seas, and lakes. They can form on all types of beaches, especially near structures like piers, jetties, or sandbars.
These currents develop due to differences in wave breaking: more waves result in higher water levels, known as wave setup, while fewer waves lead to lower levels. Water moves from high to low setup areas and then funnels offshore, forming a rip current. When strong winds blow directly toward the land from offshore, the risk of rip currents typically increases.
Types of rip currents
There are different types of rip currents. The bathymetry of the bottom controls some, while nearby structures control others. Bathymetry-controlled rip currents include channelized tip currents and focused rip currents.
The most common and understood one is the channelized rip currents. They are easier to identify, ranging in width from 5 to 100 yards. They can be as little as 3 feet deep or as deep as 10 feet, and they can be spaced apart between 50 and 500 yards. This type of rip current can happen in a fixed location for days, weeks, or months. These types of rips are easier to identify because their path is usually darker in color, which can be seen as calmer compared to the surroundings, but the surface has a choppy and rippled texture.
Focused rip currents occur in fixed locations but are controlled by alongshore variations in breaking waves, which are often created by offshore sea floor features like submarine canyons, ridges, and sandbars. The location of this kind of rip current can vary depending on the direction of the approaching wave. If looked at from above, you can spot these currents as there are swirls of turbulent water and sediment that flow offshore.
Structurally-controlled rip currents often appear near groins, jetties, and piers. They are often persistent and can form even with little wave action. They can be grouped into two types depending on how they form: shadow rip currents and deflection rip currents.
Hydrodynamically-controlled rip currents are controlled solely by hydrodynamics -- wave and current interactions -- and can occur on featureless straight beaches. It is not possible to predict the exact location and timing of hydrodynamic rip currents, as they occur frequently and often change locations. Still, it may be possible to estimate the likelihood of their formation on a given beach.
Rip currents are not rip tides. A tidal current is a distinct and separate type of current. Especially strong and variable tidal currents are sometimes called a "rip tide" or a "tidal rip". These strong tidal currents occur in areas where tidal flow is constricted, such as inlets, the mouths of estuaries, embayments, and harbors. These currents may cause drowning deaths, but they are a separate and distinct phenomenon from rip currents.
Tips if you are caught in a rip current
The NWS recommends swimming near a lifeguard if you're at the beach. If you're caught in a rip current, it’s best to remain calm. Swim parallel to the shore, not toward it, until you’re free of the current. Then swim back to land. If you're unable to escape, face the shore and call or wave for help. Make sure to check your beach conditions here, before you head into the water this summer: