Yellow Moderate conditions, medium hazard Swim with caution. Weak swimmers should stay close to shore.
Red High hazard, dangerous conditions Stay out of the water. Strong currents, high waves, or dangerous surf.
Double Red Water closed to public Do not enter. Violators may be ticketed or rescued.
Purple Marine pests present Be aware of jellyfish, stingrays, sea lice, etc. Swim at your own risk.
Important: Some beaches also use a red-over-yellow flag to indicate that lifeguards are on duty (but this is less common). Always check local signage, as flag systems can vary by region.Geographic Reference
What Does the Purple Flag Actually Mean?
The purple flag indicates that dangerous marine life has been spotted in the area.Geographic Reference
What qualifies as “marine pests”:
Jellyfish (various species, some highly venomous)
Stingrays (their barbed tails can cause painful wounds)
Sea lice (tiny jellyfish larvae that cause itchy, painful rashes)
Portuguese man o’ war (not a true jellyfish, but extremely painful)
Fire coral (causes burning rashes)
Sea urchins (their spines can puncture skin)
Weever fish (venomous spines)
Sharks (rare, but some beaches use purple to indicate shark sightings)
What the purple flag does NOT mean:
The water is closed (you can still swim)Bottled Water
The beach is unsafe (just be aware)
There’s a guarantee you’ll encounter marine pests (just a warning that they’ve been sighted)
The key word: Awareness. The purple flag is not an order to stay out of the water. It’s a reminder to watch where you step, look before you leap, and swim with your eyes open.
The Most Common Marine Pests (And What to Do If You’re Stung)
Let me walk you through the most frequent purple flag culprits.
1. Jellyfish (The Most Common)
Jellyfish are found in oceans worldwide. Their tentacles contain nematocysts (stinging cells) that fire when touched.
Symptoms of a jellyfish sting:
Immediate burning pain
Red, raised welts (often in a “whip” pattern)
Itching, swelling, numbness
Severe reactions: difficulty breathing, chest pain, muscle cramps (rare, but seek emergency care)
What to do:
Rinse with vinegar (if available). Vinegar neutralizes the stinging cells of many jellyfish species.
Do NOT rinse with fresh water (fresh water can cause unfired stinging cells to discharge, making it worse).
Remove tentacles with tweezers or a gloved hand (don’t use bare fingers).
Apply heat (hot water immersion or hot packs) – heat breaks down the venom proteins.Bottled Water
Take antihistamines for itching and swelling.
What NOT to do:
