Pacific Beach, Calif. Calm water can be deceiving. Credit: Chris Brewster/USLA

Notice the dark water moving away from shore. Credit: U.S. Army Corps of Engineers Field Research Facility at Duck, NC.

A groin off Texas. Can you find the rip current? Credit: Chris Houser, Texas A&M University, and Texas Sea Grant.

Where would you let your kids go swimming at the beaches in the photos above? Do you know how to spot a rip current? (answers below)

You can often (but not always) spot a rip current by looking for any of these clues:

1) a darker channel of seaward flowing water

2) a line of foam, seaweed or debris flowing offshore

3) a break in the incoming wave pattern

Hard structures such as jetties, groins and piers often set up permanent “structurally controlled” rip currents.

The Scripps Pier in La Jolla, for example, almost always has a weak rip current flowing along it, even when the surf is small, explains Falk Feddersen, a coastal oceanographer at Scripps Institution in Oceanography, UC San Diego. Feddersen has had California Sea Grant support to study rip currents and other nearshore processes, and is an avid surfer.

While most swimmers should avoid rip currents along groins and piers, surfers often take advantage of “rips” as free conveyor-belt rides out to the surf. Rip currents are just flows of water. Don’t panic if you are caught in one.

How did you score in finding “the rips” in the three photos above? Answers in red arrows are below.

The rip current is flowing seaward through a deeper channel. Credit: C. Brewster/USLA

A channel of churning, choppy water is sign of a rip current. Credit: USACE

The rip current is on the left side of the groin. Credit: Texas Sea Grant

June 2-8 is Rip Current Awareness Week, an educational partnership with the United States Lifesaving Association, NOAA and the National Sea Grant Program to help teach people how to stay safe at the beach and “avoid the grip of the rip.”

Written by Christina S. Johnson, csjohnson@ucsd.edu

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NOAA’s California Sea Grant College Program is a statewide, multi-university program of marine research, extension services, and education activities administered by Scripps Institution of Oceanography at the University of California, San Diego. It is one of 33 Sea Grant programs and is part of the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce. Visit our website (www.csgc.ucsd.edu) to sign up for email news or follow us on Facebook or Twitter.