About Rip Currents
Rip currents are powerful, channeled currents of water flowing away from shore. They typically extend from the shoreline, through the surf zone, and past the line of breaking waves. Rip currents can occur at any beach with breaking waves, including the Great Lakes.
Rip currents can be killers. 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.
The greatest safety precaution that can be taken is to recognize the danger of rip currents and always remember to swim at beaches with lifeguards. The United States Lifesaving Association has calculated the chance that a person will drown while attending a beach protected by USLA affiliated lifeguards at 1 in 18 million. If caught in a rip current at an unguarded beach, how you respond could make the difference between life and death.
The United States Lifesaving Association, in partnership with NOAA’s National Weather Service and National Sea Grant Program, is working together to raise awareness about the dangers of rip currents. Research is also being conducted in order to develop and improve the ability to predict the occurrence and strength of rip currents. The goal of the awareness campaign and research is to reduce the number of rip current related fatalities.
With increasing coastal populations, rip currents will continue to be a serious hazard at surf beaches. This web site is designed to provide educational material as well as real time information about the rip current risk. The time you take to understand rip currents can help you protect yourself and your loved ones when visiting the beaches.
Why Rip Currents Form
As waves travel from deep to shallow water, they will break near the shoreline. When waves break strongly in some locations and weakly in others, this can cause circulation cells which are seen as rip currents: narrow, fast-moving belts of water traveling offshore.
Why Rip Currents are Dangerous
Rip currents are the leading surf hazard for all beachgoers. They are particularly dangerous for weak or non-swimmers. Rip current speeds are typically 1-2 feet per second. However, speeds as high as 8 feet per second have been measured–this is faster than an Olympic swimmer can sprint! Thus, rip currents can sweep even the strongest swimmer out to sea.
Over 100 drownings due to rip currents occur every year in the United States.More than 80% of water rescues on surf beaches are due to rip currents.
Diagram courtesy of the NWS Southern Region Headquarters
When Rip Currents Form
Rip currents can be found on many surf beaches every day. Under most tide and sea conditions the speeds are relatively slow. However, under certain wave, tide, and beach profile conditions the speeds can quickly increase to become dangerous to anyone entering the surf. The strength and speed of a rip current will likely increase as wave height and wave period increase. They are most likely to be dangerous during high surf conditions as the wave height and wave period increase.
Where Rip Currents Form
Rip currents most typically form at low spots or breaks in sandbars, and also near structures such as groins, jetties and piers. Rip currents can be very narrow or extend in widths to hundreds of yards. The seaward pull of rip currents varies: sometimes the rip current ends just beyond the line of breaking waves, but sometimes rip currents continue to push hundreds of yards offshore.
How to Identify Rip Currents
Look for any of these clues:
- a channel of churning, choppy water
- an area having a notable difference in water color
- a line of foam, seaweed, or debris moving steadily seaward
- a break in the incoming wave pattern
None, one, or more of the above clues may indicate the presence of rip currents. Rip currents are often not readily or easily identifiable to the average beachgoer. For your safety, be aware of this major surf zone hazard. Polarized sunglasses make it easier to see the rip current clues provided above.
How to Avoid and Survive Rip Currents
Learn how to swim!
|Photo courtesy of the U.S. Army Corps of Engineers
Field Research Facility at Duck, NC.
- Never swim alone.
- Be cautious at all times, especially when swimming at unguarded beaches. If in doubt, don’t go out!
- Whenever possible, swim at a lifeguard protected beach.
- Obey all instructions and orders from lifeguards.
- If caught in a rip current, remain calm to conserve energy and think clearly.
- Don’t fight the current. Swim out of the current in a direction following the shoreline. When out of the current, swim towards shore.
- If you are unable to swim out of the rip current, float or calmly tread water. When out of the current, swim towards shore.
- If you are still unable to reach shore, draw attention to yourself: face the shore, wave your arms, and yell for help.
- If you see someone in trouble, get help from a lifeguard. If a lifeguard is not available, have someone call 9-1-1 . Throw the rip current victim something that floats and yell instructions on how to escape. Remember, many people drown while trying to save someone else from a rip current.
Rip Current Myth
A rip current is a horizontal current. Rip currents do not pull people under the water–-they pull people away from shore. Drowning deaths occur when people pulled offshore are unable to keep themselves afloat and swim to shore. This may be due to any combination of fear, panic, exhaustion, or lack of swimming skills.
In some regions rip currents are referred to by other, incorrect terms such as rip tides and undertow. We encourage exclusive use of the correct term – rip currents. Use of other terms may confuse people and negatively impact public education efforts.
Glossary of Terms
Backwash—The seaward return of the water following the uprush of the waves. Also called backrush or run down.
Breaker— A wave that has become so steep that the crest of the wave topples forward, moving faster than the main body of the wave.
Breaker zone—The zone within which waves approaching the coastline commence breaking, typically in water depths of between 5 m and 10 m.
Cusp—One of a series of short ridges on the shore separated by crescent-shaped troughs spaced at more or less regular intervals. Between these cusps are hollows. The cusps are spaced at somewhat uniform distances along beaches.
Embayment—An indentation in a shoreline forming an open bay.
- A semi-enclosed coastal body of water which has a free connection with the open sea. The seawater is usually measurably diluted with freshwater.
- The part of the river that is affected by tides.
- The zone or area of water in which freshwater and saltwater mingle and water is usually brackish due to daily mixing and layering of fresh and salt water.
Feeder current—The currents which flow parallel to shore before converging and forming the neck of a rip current.
Groin—A shore-protection structure (built usually to trap littoral drift or retard erosion of the shore). It is narrow in width (measured parallel to the shore) and its length may vary from tens to hundreds of meters (extending from a point landward of the shoreline out into the water). Groins may be classified as permeable (with openings through them) or impermeable (a solid or nearly solid structure).
Head of a rip—That part of a rip current circulation typically located beyond the breakers, marked by a spreading out or fanning of the circulation. It is here where the velocity and strength of the rip current circulation begins to weaken considerably.
Jetty—On open seacoasts, a structure extending into a body of water to direct and confine the stream or tidal flow to a selected channel, or to prevent shoaling. Jetties are built at the mouth of a river or entrance to a bay to help deepen and stabilize a channel and facilitate navigation.
Littoral currents—A current running parallel to the beach and generally caused by waves striking the shore at an angle.
Littoral drift—The sedimentary material moved parallel to the shoreline in the nearshore zone by waves and currents.
Longshore current—A current located in the surf zone, moving generally parallel to the shoreline, generated by waves breaking at an angle with the shoreline, also called the alongshore current.
Neck—That part of a rip current circulation located in the surf zone, marked by a narrow band of swiftly moving, seaward flowing water. It is here where velocity of the circulation is at a maximum, and where most rip current drowning deaths occur.
Rip Channel—A channel cut by the seaward flow of a rip current, usually crossing a sandbar.
Rip current—A relatively small-scale surf-zone current moving away from the beach. Rip currents form as waves disperse along the beach causing water to become trapped between the beach and a sandbar or other underwater feature. The water converges into a narrow, river-like channel moving away from the shore at high speed. A rip current consists of three parts: the feeder current flowing parallel to the shore inside the breakers; the neck, where the feeder currents converge and flow through the breakers in a narrow band or “rip”; and the head, where the current widens and slackens outside the breaker line.
Rip Tide—Rip currents are not rip tides. A distinctly separate type of current includes both ebb and flood tidal currents that are caused by egress and ingress of the tide through inlets and the mouths of estuaries, embayments and harbors. These currents may cause drowning deaths, but these tidal currents or jets are a separate and distinct phenomenon from rip currents. Recommended terms for this phenomenon
include ebb jet or tidal jet.
Run-up—The rush of water up a beach due to the breaking of a wave. The amount of run-up is the vertical height above stillwater level that the rush of water reaches.
Sand bar—An offshore ridge or mound which is submerged (at least at high tide), especially at the mouth of a river or estuary, or lying parallel to, and a short distance from, the beach.
Shoreline—The intersection of the ocean water surface with the shore or beach.
Significant Wave Height—The average wave height of the one-third highest waves of a given wave group.
Surf Zone—Area of water between the high tide level on the beach and the seaward side of breaking waves.
Swell—Wind-generated waves that have traveled out of their source region, usually over a considerable distance. Swell waves exhibit a more regular and longer period with flatter crests than choppy, locally generated wind waves.
Tide—The periodic rising and falling of the water which results from gravitational attraction of the Moon and Sun acting upon the rotating Earth.
Undertow—Different than a Rip Current!
Wave Height—The vertical distance between the crest and the preceding trough of a wave.
Wind Waves—Waves generated by, and directly attributable to local winds, as opposed to swell waves, which have traveled over a considerable distance and produced by winds occurring at some previous time.
Definitions taken from:National Weather Service Directives System, NOAA Coastal Services Center and National Weather Service Rip Current Technical Team