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Do you know which beach flags mean dangerous swimming conditions?

By Ashley Williams, AccuWeather staff writer

On your next trip to the beach, keep in mind that conditions might not be as safe as they may appear. Lifeguards will often fly flags of different colors to notify beachgoers of any present dangers.

The United States Lifesaving Association and the International Lifesaving Federation have developed a flag warning system, used worldwide, that helps to notify swimmers of any changes in conditions along the beach and in the ocean.

“We have pretty well standardized flags here in the U.S.,” said Dr. Stephen Leatherman, professor and director of the Laboratory for Coastal Research at Florida International University.

Although additional colors are sometimes incorporated into the system for different beaches in various parts of the country, the system generally follows that of traffic lights, where green means go, yellow means caution and red means stop.

Beach warning flag - AP Photo

A warning flag flies from a lifeguard's vehicle as he patrols the beach during a break in the rain and wind storms in Virginia Beach, Virginia, on Saturday, Sept. 3, 2015. (AP Photo/Steve Helber)

“Flags will get your attention,” Leatherman said. “They’re generally better [at grabbing people’s attention] than signs.”

Unfortunately, there are many people that aren’t very competent when swimming at the beach, Dr. Tom Griffiths, president and founder of the Pennyslvania-based Aquatic Safety Research Group, told AccuWeather.

“They may know how to swim, but the only experience many of them have may be in swimming pools, ponds and lakes, and you have a whole set of hidden hazards at the beach," he said.

Recognizing the meanings behind these flag colors can help save your life in unfavorable swimming conditions.

Green flag

When you spot a green flag along the beach, swimming or recreational conditions are considered ideal, according to Elyssa Finkelstein, strategic communications manager for the Florida Department of Environmental Protection.

“The green flag signifies low hazards and calm conditions,” Finkelstein said. “Beachgoers can enjoy the water and swimming while remaining alert to changing conditions and currents.”

Yellow flag

Take caution when approaching the water if a yellow flag is flying, said Leatherman, as it could mean that waves are higher than usual.

"The waves may be a little larger or rip currents may be present, but if you have any concerns, talk to a lifeguard to see what the yellow flag is signaling,” Leatherman said.

Those who are not strong swimmers should take extra care on the beach if there’s a yellow flag present, he said.

“[However], even if you are a good swimmer, you do need to know something about rip currents, because the response that nature tells us is to swim back to shore,” Leatherman said. “That would be against the rip current, and even great swimmers can drown in a case like that.”

Red flag

If a lifeguard sends a red flag into the air, it means that hazardous conditions, including strong surf or currents, are present. Beachgoers are advised to stay out of the water, experts say.

“I think we all understand that red means danger,” Leatherman said. That’s telling you that things are bad out there."

Shorebreak is a particularly dangerous, but uncommon, beach hazard that happens when the ocean’s waves break directly on the shore.

“The wave picks you up and drive you headfirst into the beach, which could break your neck,” Leatherman said.

In Cape Cod, Massachusetts, the presence of sharks will prompt lifeguards to fly a red flag with the outline of a shark on it, according to Leatherman.

“They’ve had some great white sharks starting to show up because of the seal population increasing,” he added.

Double red flag

The double red flag means the water is completely closed to the public.

“Often, this means very dangerous ocean conditions, such as strong rip currents, and beachgoers should stay out of the water when these flags are present,” Finkelstein said.

Leatherman added that beachgoers can even be arrested when entering the beach if a double red flag is flying.

"Once, when vacationing on the Outer Banks of North Carolina, we were evacuated because of an incoming hurricane,” Griffiths said. “The ocean was definitely dangerous for anyone who entered it, but many people stayed in the ocean with the double red flags flying and the lifeguards screaming at them to get out of the water.”

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Experts advise swimmers always to heed beach warning flags to avoid hazardous conditions.

Purple flag

“This flag indicates that there may be marine wildlife present, such as jellyfish, stingrays and other dangerous fish,” Finkelstein said. “Beachgoers should be alert and cautious of these animals.”

“Beach warning flags are often visible as [swimmers] approach a beach, which immediately makes them aware of ocean conditions so they can decide whether or not to go in the water,” she added. “Without warning flags, beachgoers might not be aware of dangerous currents, surf, wildlife or other risky conditions.”

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