Alright, so you know all those colored flags they put up at the beach? Most people know the basics. Green = the water is good, red = you are probably going to die if you swim, yellow = “okay, it is not great, but maybe consider swimming.” But then there is that other flag. The purple flag. Have you ever noticed it?
I know I must have strolled past tons of purple flags and never even thought about them until one day it just hit me. What the hell is a purple flag? I mean, I thought I had the beach flag system figured out. Green, yellow, red, and even the one that says double red, and just basically means go home. But a purple flag? That is not a normal flag designation, is it?
Turns out it absolutely is. Also, it is not some wannabe lifeguard just painting the tower.

So I started looking it up. A purple flag means there are… marine pests in the water. Which is such a strange and polite term. Pests? That could really be anything from an annoying bug to maybe something that harms you and ruins everything you had planned for that day. In this case, it is more the latter; think jellyfish. Think stingrays. And maybe some other creatures with barbs and spines that don’t want you around and are going to let you know if you try to hang out with them.
Alright, now we know. If you see a purple flag flapping in the breeze, there could be things in the water that sting, poke, or zap you. This does not mean there is a jellyfish invasion, but there could be. Basically, a purple flag is the beach’s way of saying, “You can go in; however, do not be surprised if something brushes against your ankle and you come out itchy and angry.”
Of course, the more I think about it, the more it makes sense why the flag exists. Most of us, myself included, think about crashing waves, riptides, and all of that kind of dramatic stuff. But maybe when the ocean’s all flat and sun-drenched and pretty, there is nothing to worry about—well, until those jelly blobs are circling under you waiting to sting you! The purple flag isn’t meant for warning about dangers you see. It’s more warnings about dangers you can’t see!
Now I know what you are thinking… but what if it’s green and purple? Like, perfect water, but… jelly blobs?! Yup. That happens. It kind of makes your mind short-circuit because your brain sees “lovely” while the little purple flag is like, “You’re not alone out there, buddy.”

Honestly, it’s kind of brilliant. The ocean does not “talk,” right? But this is as close as we get. A purple flag is basically the ocean whispering to you, “This stuff I am hiding in me today is a normal part of my ecosystem. Proceed accordingly.”
Anyway! Once I figured it out, I started noticing the purple flag, occasionally, even on the days that are loveliest by the beach! You can always spot the people who notice the purple flag and are casually sliding their towels a little farther back. Or the kids who did not notice and are heckin’ running in—then maybe half an hour later are running back out with red welts on their legs and swearing their vengeance to the sea.
So alright. Green = go. Yellow = uh, be careful. Red = nope. Double red = really nope. And purple flag = let’s just say it’s a heads-up. A heads-up doesn’t mean, “you’re going to die”; rather, it’s saying, “there is some stuff in here that may not want you floating out.” Not dramatic, but not decorative either!
I think what I like about it, actually, is how unassuming it is. There is something humbling, perhaps, about reminding yourself, you are not the only one in the water. This is no big, salty floating pool—you are hanging out, swimming amidst a sensitive, living ecosystem—and you’re a guest!
So the next time you are doing your beach day, and you’ve got your beach chair and your SPF 50 sunscreen and you notice that weird little purple flag waving back and forth like it knows something that you do not… well, pay attention. It kind of does.