Flags flapping at the beach aren't just for show. The International Lifesaving Federation and the United States Lifesaving Association maintain a recommended colour code that lifeguards use to signal conditions, and most of us can guess the basics: solid red means high hazard. But purple tends to leave swimmers puzzled.
A purple flag doesn't mean the water is rough or swimming is banned. It warns that potentially dangerous marine life has been spotted in higher-than-usual numbers — think jellyfish, stingrays, or Portuguese man o' war. In other words, the danger is alive and floating, not the surf itself.
Importantly, purple doesn't close the beach. That's the job of a double red flag. Purple simply tells you to stay alert and take precautions before getting in. A few localities do fly purple for shark sightings, even though the USLA specifically says the flag isn't meant for that — because the flag system is a recommendation rather than a law, individual beaches can adapt the meanings. If you're unsure what triggered the warning, check the notice board near the lifeguard stand or just ask the lifeguard directly.
If you do head into the water under a purple flag, a couple of cheap precautions go a long way. A wetsuit or long-sleeve rash guard shields your skin from stings, and many seasoned beachgoers carry vinegar, which is widely recommended as a first-aid item for stings. For anyone travelling to Florida, this matters more than you might think: Portuguese man o' war are a regular sight around Palm Beach, and their numbers often trigger the flag. They drift worldwide, though, so it's worth recognising one wherever you swim.
Also known as blue bottles, Portuguese man o' war are easy to identify — a bluish, balloon-like float sitting on the surface. The real hazard is what you can't easily see: long tentacles trailing below or down-current. Spot one and the safest move is to swim well clear, not just of the float but of anything hanging beneath it.
Why does this matter for travellers? Because flag systems vary by country and even by county, and assuming a purple flag means the same thing everywhere can lead to a painful afternoon. Treat it as a prompt to pause: check the board, ask a local, and decide whether a swim is worth the risk that day. Jellyfish seasons are increasingly unpredictable, so even beaches you've visited for years might raise the flag when you least expect it.
The takeaway is simple. Red means dangerous water, double red means stay out, and purple means the creatures are out — but the beach is still open. A quick glance at the flagpole before you unpack your towel is one of the easiest safety habits any beach holiday can offer, and it costs nothing. Keep the vinegar in your beach bag, keep an eye on the water's surface, and you'll be ready for whatever the flag is trying to tell you.
