If You See Square Waves in the Ocean, Get Out of the Water Immediately

[00:00:00]Every summer the sea posts its warnings in plain sight in the shape of the waves, the color of the water, even the foam on the sand. Lifeguards read these signs all day long. Most swimmers never learn a single one. Some of the signs below look dramatic and are mostly harmless. You'll meet the famous square waves first. But one entry on this list is the exact opposite. It kills more beachgoers than everything else here combined and it looks like the [music] safest, calmest spot on the whole beach.

[00:00:26]It's waiting near the end and once you can spot it, you'll see it on every beach you ever visit again.

[00:00:31]But before we start, smash the like button and make sure to subscribe if you haven't and hit that notification bell so that you won't miss any new stories.

[00:00:39]The strange part is that the ocean rarely hides its danger. It leaves clues everywhere. A line of foam moving the wrong way, a flag tourist photograph without understanding, [music] a patch of brown water everyone assumes is just mud. None of these signs requires expert equipment. [music] You only need to know what you're looking at before you step in. When two wave systems [music] cross at an angle, the sea turns into a grid of squares, a cross sea. It's mesmerizing. It's the most photographed wave pattern [music] on Earth. The lighthouse views on France's Île de Ré made it famous and the internet has warned you about it for years. The truth, it is a real hazard for boats and for swimmers caught in the confused multi-directional currents beneath. But it's rarer and less lethal than the ads claimed. The rule is simple. Admire from the sand. If [music] you're in the water when the surface turns to graph paper, come in calmly.

[00:01:28]The currents under a cross sea pull two directions at once and that's a fight you don't need. Two, a gap of calm flat water between breaking waves. File this one away. We'll come back to it at the end because it's the killer on this list.

[00:01:41]>> [music] >> For now, just the picture. Waves breaking white to the left, waves breaking white to the right and between [music] them a smooth dark calm looking corridor where the water seems gentle.

[00:01:50]Swimmers head straight for it every single day because it looks like the easy place to swim. Remember it and the one counterintuitive move that saves your life in it.

[00:02:00]Everyone knows red means danger. Almost nobody can read the purple flag, [music] and it flies on hundreds of beaches every summer. Purple means dangerous marine life present, usually jellyfish swarm, sometimes [music] Portuguese man-o-war, stingrays, or sea lice. It does not mean sharks, that's a cleared beach in a different protocol entirely.

[00:02:19]>> [music] >> The trap. Purple often flies on gorgeous, calm, perfect-looking days.

[00:02:23]The same warm currents that make great [music] swimming carry the jellyfish in.

[00:02:27]See purple? Ask the lifeguard what's in [music] the water before your kids are in it. They love being asked. Four, sneaker waves, the reason locals never turn their [music] back. On certain coasts, the US Pacific Northwest most famously, the sea sends a wave every 10 or 20 minutes [music] that's vastly larger than everything before it, surging dozens of meters further up a dry beach. They're called sneaker waves because that's what they do, arrive without warning, knock adults off their feet, [music] and pull them back over log-strewn sand. The signs locals read, fresh wet sand far above the current waterline. [music] The last sneaker signature, driftwood logs lying high on the beach, the sea put them there [music] and can float a two-ton log in ankle-deep water, and warning signs you should take literally. The rule on [music] sneaker coasts is scripture, never turn your back on the ocean. If the sea abruptly retreats, exposing [music] sand, rocks, and flapping fish where water just was, you are not watching an odd tide, you're watching the single clearest natural tsunami warning that exists, and you may have only minutes.

[00:03:28]>> [music] >> It's called drawback, of the tsunami arriving before its crest. People walk out to look at the stranded [music] fish, survivors run uphill. Teach your kids this one sentence and consider this page worth it. If the ocean runs away, you run, too, inland and uphill immediately, and don't come back for hours. The same applies to any unexplained [music] fast, sustained change in sea level. Six, the champagne foam line that smells wrong. Seafoam is usually harmless, churned up algae and organic matter, the ocean's cappuccino.

[00:03:57][music] But a thick, persistent brownish or reddish foam with a chemical or rotten smell can mark a harmful algal bloom, a red [music] tide cousin, and on those days the spray itself can set off coughing fits and sting [music] eyes, while shellfish from the area become genuinely dangerous. The tells: discolored water, rust brown or pea green streaks, dead fish along the tideline, and that wrongness in the air.

[00:04:21]Swim elsewhere, keep dogs out of the foam. Dogs are the most frequent victims, and skip the beachside mussels that week. It looks like a child's lost party balloon. Translucent [music] blue violet, glossy, the size of your palm lying on the wet sand. It's a Portuguese man-of-war, and the tentacles trailing invisibly meters across the sand sting ferociously [music] for days after the animal is dead. Beached ones injure more people than swimming ones, mostly children who pick them up and [music] adults who nudge them barefoot. One on the sand means more in the water. They drift in flotillas on the wind. The protocol: look, photograph, tell the lifeguard, touch nothing, and [music] check the purple flag, because this is exactly what it flies for.

[00:05:01]Eight. Brown churning water near a river mouth or after rain. That tea-colored water where the river meets the beach isn't just ugly, it's the most statistically loaded water on the coast.

[00:05:11][music] River mouths combine outflowing currents that work like conveyor belts, sudden depth changes, debris you [music] can't see, runoff bacteria after storms, and on coast where it's relevant, they're where predators feed, because that's where the murk and the baitfish are. [music] Lifeguards play in rule: don't swim at river mouths, and skip the ocean for 72 hours after heavy rain. The runoff alone, the bacterial kind, sends [music] more swimmers to the doctor than anything with teeth ever will. Here's a sign hiding in plain sight: watch what [music] floats. Waves push everything, foam, kelp that escaped, beach ball, toward the shore. So when you spot a line of foam or debris traveling steadily away from the beach cutting out through the surf like it has an appointment, you're looking at water leaving the beach in a hurry.

[00:05:56]>> [music] >> A current strong enough to carry whatever floats, including swimmers.

[00:05:59]Lifeguards literally use this to spot trouble from the tower. 10. Square flag and double flag systems [music] most visitors misread. Quick world tour because flag illiteracy hurts tourists most. Red over red, two stacked red [music] flags equal sign water closed, full stop. Red and yellow halved flags equal [music] sign lifeguarded swimming zone, swim between them, not wherever looks nice. Black and white quartered [music] equal sign surfboard zone, no swimmers. Yellow equal sign caution, weak swimmer stay shallow. Green on beaches that use it equal sign calm conditions and famously the most dangerous flag of all because it switches brains off. And no flag at all on an unfamiliar beach doesn't mean safe, it usually means nobody is watching. 30 seconds reading the flag pole beats [music] a very bad afternoon.

[00:06:47]Back to page three. That smooth, dark, calm-looking [music] lane between the breaking waves is a rip current, a narrow river of water flowing out to sea often faster than an Olympic swimmer. It looks calm precisely because it's deep, moving water where waves don't break. Rips cause the overwhelming majority of beach rescues and dozens of drownings every year, more than sharks, jellyfish, and square waves combined decade after decade. [music] Now the part that saves lives because it's counterintuitive. A rip does not pull you under, it pulls you [music] out.

[00:07:18]People drown fighting it head on toward the beach until exhaustion. The escape.

[00:07:22]Don't swim against it, swim parallel to the beach until you're out of the narrow current. They're rarely wider than a bus is long. Then ride the waves in at an angle.

[00:07:31]>> [music] >> Can't make progress? Float on your back, keep breathing, wave one arm high.

[00:07:35]Floating in a rip is survivable for a long time, fighting one isn't. Rip identified, escape memorized. [music] You now know more than 90% of the people on any beach this summer. The sea publishes its forecast in plain [music] sight. Squares mean confused currents. A fleeing tide means run. Purple means tentacles. [music] Driftwood means sneakers. Brown means stay out. And calm in the wrong place means [music] everything. Print the rip current rule into the family, parallel then in. And [music] if this list earned its keep, the companion piece pays the same way, the nine warning signs [music] hikers ignore in the mountains, including the cloud formation that gives you exactly 20 minutes notice and the reason experienced hikers turn around when the forest goes [music] quiet.