A purple flag at the beach signals dangerous marine life—an often-ignored warning that could protect you from serious harm in the water

Most people step onto a beach expecting to watch for waves, sunburn, or maybe strong currents.

Very few expect the danger to already be moving silently beneath the water.

That’s exactly why the purple flag exists.

If you’ve ever seen a purple flag flying near a lifeguard tower and wondered what it meant, you’re not alone. Unlike red or yellow flags—which continue reading …