WEBVTT - How Do Rip Currents Work?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,

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<v Speaker 1>Lauren bobobum here. If you've been around beach is enough,

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<v Speaker 1>you've probably run across the sign at some point with

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<v Speaker 1>a warning to avoid a particular area because of a

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<v Speaker 1>rip current. Rip currents are responsible for about one hundred

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<v Speaker 1>and fifty deaths every year in the United States. In Florida,

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<v Speaker 1>they kill more people on average than thunderstorms, hurricanes, and

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<v Speaker 1>tornadoes combined, and they're the number one concern for beach lifeguards.

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<v Speaker 1>About eighty percent of all beach rescues are related to

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<v Speaker 1>rip currents. These scary statistics exist partially because lots of

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<v Speaker 1>swimmers aren't familiar with how rip currents work and how

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<v Speaker 1>to survive if you happen to get caught in one.

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<v Speaker 1>So today let's talk about all that and how to

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<v Speaker 1>hopefully avoid them in the first place. A rip current

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<v Speaker 1>is a narrow but powerful current of water running erpendicular

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<v Speaker 1>to a beach out into the ocean or lake. These

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<v Speaker 1>currents may extend hundreds of feet or meters outward, but

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<v Speaker 1>they're typically less than thirty feet or nine meters wide,

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<v Speaker 1>and they can move it a pretty good clip, often

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<v Speaker 1>five miles or eight kilometers an hour or faster, which

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<v Speaker 1>doesn't sound that fast until you consider that it's like

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<v Speaker 1>being dragged at a brisk jog by something that doesn't

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<v Speaker 1>tire out. A rip currents form when water gets blocked

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<v Speaker 1>in near a beach and then suddenly finds a way

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<v Speaker 1>back out to the open water and rushes out. They're

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<v Speaker 1>dangerous because they're unpredictable. This is different from ripped tides,

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<v Speaker 1>which happen like liquid clockwork, when the tide pulls water

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<v Speaker 1>out through an inlet or similar into the sea. They're

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<v Speaker 1>still dangerous and can be more powerful than rip currents,

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<v Speaker 1>but at least they're predictable. Always heed any warning signage

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<v Speaker 1>you see at a waterfront. Rip currents are also different

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<v Speaker 1>from undertoe. Undertow describe the water that washes back from

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<v Speaker 1>the shore where the waves break up on the land.

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<v Speaker 1>It flows underneath the next wave and may continue out

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<v Speaker 1>along the seafloor into the open water. Undertow is a normal,

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<v Speaker 1>continual feature of any body of water big enough to

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<v Speaker 1>have waves. It's what you feel when the receding water

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<v Speaker 1>pulls at your feet for a moment before the next

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<v Speaker 1>wave hits, but it's only strong right at the shoreline

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<v Speaker 1>and usually not dangerous to anyone but small kids who

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<v Speaker 1>might get knocked over. They can wind up below the

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<v Speaker 1>water line and struggle to get back up. Always keep

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<v Speaker 1>an eye on kids in the water. Rip currents, by contrast,

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<v Speaker 1>move along the surface of the water. They're so hazardous

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<v Speaker 1>because they catch you off guard. One minute you're bobbing

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<v Speaker 1>along peacefully in the surf, and the next you're being

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<v Speaker 1>dragged out to sea at top speed. They occur in

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<v Speaker 1>all kinds of weather and on a wide range of beaches.

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<v Speaker 1>Unlike a violent, choppy water, rip currents can look calm,

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<v Speaker 1>so you might not noticeable until you're right in the

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<v Speaker 1>middle of it. Rip currents are anomalous occurrences, but they're

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<v Speaker 1>borne out of ordinary, everyday waves. On a basic level,

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<v Speaker 1>you can think of waves as traveling fluctuations in water level.

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<v Speaker 1>Some external force off in the wind pushes on the water,

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<v Speaker 1>creating a swell, which is passed along the surface. The

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<v Speaker 1>energy of the wave, which may be built up by

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<v Speaker 1>more pressure from the wind, is passed from water molecule

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<v Speaker 1>to water molecule. The water itself doesn't actually travel much.

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<v Speaker 1>It mostly just bobs up and down, only the energy

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<v Speaker 1>keeps going until the swells reach the shore. In areas

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<v Speaker 1>with a rocky shore, the wave breaks as it's deflected.

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<v Speaker 1>On a sandy beach with a gently sloping shore, the

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<v Speaker 1>swell pushes up hill. The climb up the beach drains

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<v Speaker 1>the energy from the breaking waves, and the water eventually

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<v Speaker 1>flows downhill back to the sea as undertow. Normally, undertow

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<v Speaker 1>move with minimal force. The slight slope of the beach

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<v Speaker 1>effectively spreads out the force over a great distance, so

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<v Speaker 1>it's not particularly strong at any one point, and since

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<v Speaker 1>it's weaker than the opposing force of incoming waves, the

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<v Speaker 1>receding flow usually won't carry you out into deeper water.

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<v Speaker 1>A rip current occurs when the receding flow becomes concentrated

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<v Speaker 1>in a particular area. There are a number of things

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<v Speaker 1>that can cause this, but the most common is a

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<v Speaker 1>break in a sand bar. Sandbars are long, narrow hills

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<v Speaker 1>of accumulated sand along the outer part of a shore.

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<v Speaker 1>They are formed by the motion of the waves and tides.

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<v Speaker 1>Some sandbars stay short, but some can build up pretty

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<v Speaker 1>tall and may even peak above the water's surface. When

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<v Speaker 1>a large sand bar forms, it can produce a sort

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<v Speaker 1>of basin along the shoreline. Incoming waves can rise up

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<v Speaker 1>over or move up against the sand bar with enough

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<v Speaker 1>force to push water into the basin, but the receding water,

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<v Speaker 1>moving the long the seafloor, has a hard time making

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<v Speaker 1>it back over the sandbar to return to the open water.

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<v Speaker 1>This is something like a bathtub with the drain plugged up.

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<v Speaker 1>Just as the water in a bathtub is being pulled

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<v Speaker 1>downward by gravity but is blocked by the drain plug,

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<v Speaker 1>the receding wave is being coaxed to flow back off

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<v Speaker 1>shore by the undertow and gravity, but is kept in

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<v Speaker 1>by the sand bar. In some cases, the pressure of

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<v Speaker 1>the water trying to recede may be strong enough to

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<v Speaker 1>break through part of the sand bar. Other times, water

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<v Speaker 1>will flow along parallel to the beach until it reaches

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<v Speaker 1>a low point of the sandbar. In either case, once

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<v Speaker 1>it finds an opening, the water that's piled up inside

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<v Speaker 1>the basin rushes out to sea, just as the water

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<v Speaker 1>in your bathtub rushes out when you unplug the drain.

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<v Speaker 1>The resulting rip current pushes water from the basin through

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<v Speaker 1>the narrow opening and spits it out on the other

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<v Speaker 1>side of the sandbar. Because waves keep pushing more water

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<v Speaker 1>into the basin between the sand bar and the beach,

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<v Speaker 1>the rip current may continue for several minutes or even

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<v Speaker 1>several hours. Some rip currents are brief occurrences, but others

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<v Speaker 1>are long term fixtures of an area. Typically, the strongest

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<v Speaker 1>part of a rip current is the direct line between

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<v Speaker 1>the sand bars opening to the water's edge, but the

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<v Speaker 1>current will also pull in surrounding water from each side

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<v Speaker 1>of the basin. In this way, a rip current might

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<v Speaker 1>pull you sideways parallel to the beach before it pulls

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<v Speaker 1>you outward away from the beach. Once the receding water

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<v Speaker 1>makes its way through the opening in the sand bar,

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<v Speaker 1>the pressure equalizes and the current will dissipate. You can

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<v Speaker 1>sometimes see rip currents from the beach. They disrupt incoming

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<v Speaker 1>waves and can stir up sand or sediment from the seafloor,

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<v Speaker 1>So keep an eye out for a narrow break in

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<v Speaker 1>the waves or for a column of froth or differently

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<v Speaker 1>colored water pushing off shore. If you get caught in

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<v Speaker 1>a rip current, it's crucial that you keep your wits

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<v Speaker 1>about you. A rip currents may knock you off your

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<v Speaker 1>feet in shallow water, and if you thrash or get disoriented,

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<v Speaker 1>you might end up being pulled along under the surface,

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<v Speaker 1>but if you relax your body and float, the current

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<v Speaker 1>should keep you near the surface. Your first instinct might

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<v Speaker 1>be too swim against the current back to shallow water.

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<v Speaker 1>In most cases, even if you're a strong swimmer, this

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<v Speaker 1>will only wear you out. Rip currents can be way

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<v Speaker 1>too strong to fight head on. Instead, swim sideways parallel

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<v Speaker 1>to the beach and out of the current. Think of

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<v Speaker 1>it like your wiley coyote. You want to run sideways

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<v Speaker 1>out of the way of the boulder and not try

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<v Speaker 1>to outrun it. If you can break sideways out of

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<v Speaker 1>the current, you can swim back to shore more easily

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<v Speaker 1>with help from the waves. But if it's too hard

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<v Speaker 1>to swim parallel while you're being dragged outward by the current,

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<v Speaker 1>just wait until it carries you past the sandbar. The

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<v Speaker 1>water will be much calmer there and you can get

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<v Speaker 1>clear of the rip current before heading back in. If

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<v Speaker 1>you don't think you can swim all the way back

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<v Speaker 1>to the beach, get past the rip current and just

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<v Speaker 1>tread water. Call for help, signal the people on the beach,

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<v Speaker 1>and if all us fails, concentrate on floating and let

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<v Speaker 1>the waves help carry you in. People drown when they

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<v Speaker 1>expend all their energy brashing or struggling to swim. To

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<v Speaker 1>survive a rip current or any crisis in the water,

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<v Speaker 1>you have to keep calm and conserve your energy. If

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<v Speaker 1>you're on the beach and see someone else caught in

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<v Speaker 1>a rip current, call for help from a lifeguard or

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<v Speaker 1>emergency services. Don't dive in and try to swim out

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<v Speaker 1>to the person unless you are both very sure of

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<v Speaker 1>yourself and the situation, and you have a raft, buggy board,

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<v Speaker 1>or life preserver with you to give to the person

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<v Speaker 1>who's struggling. The most effective way to fight rip currents

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<v Speaker 1>is to follow basic swimming safety. Never go in deep

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<v Speaker 1>water alone, and if you aren't a strong swimmer, stick

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<v Speaker 1>to the shallows. Ideally, you should only swim in areas

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<v Speaker 1>where there's a lifeguard or other strong swimmer on the

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<v Speaker 1>beach who can keep an eye on things. Today's episode

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<v Speaker 1>based on the article what is a ripcurrent? On HowStuffWorks

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<v Speaker 1>dot Com written by Tom Harris. Brain Stuff is production

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<v Speaker 1>of iHeartRadio in partnership with how stuffworks dot Com and

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<v Speaker 1>is produced by Tyler Klaange. For more podcasts from my

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<v Speaker 1>heart Radio, visit the iHeartRadio app, Apple podcasts, or wherever

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<v Speaker 1>you listen to your favorite shows.