HAWAII GUIDE · 2026

Red Flags at Hawaii Beaches

What to Watch For

Checking live advisories…

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If It Looks Brown, Donʻt Swim

Never enter the ocean when the water appears brown or murky, even if no advisory is posted. Hawaii is often slow to test beaches and update advisories — not every beach is monitored. After heavy rain, wait at least 72 hours and until the water clears before swimming.

Learn more about brown water advisories →

Question 1

What does brown water at a Hawaii beach mean?

Brown or murky water indicates runoff from streams carrying bacteria, sediment, and pollutants. Never enter the ocean when the water appears brown. Wait at least 72 hours after heavy rain and until the water clears.

Question 2

What do the colored flags at Hawaii beaches mean?

Red flags mean high hazard (strong currents, high surf). Yellow flags mean moderate hazard. Green flags mean low hazard. No flag does not mean safe conditions. Always assess conditions yourself.

Question 3

How do I know if a Hawaii beach has a water quality advisory?

Check the Hawaii DOH Clean Water Branch website or use Safe to Swim Hawaii for current advisories. Posted signs at the beach may not be updated quickly. Not all beaches are monitored.

⚠️ The 72-Hour Rain Rule

The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain, even if the water looks clear. Bacteria and pollutants from runoff can linger in the water longer than the brown color does.

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Brown Water Advisory Guide → Swimming After Rain in Hawaii → All Hawaii Beaches & Hotels →

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⚠️ Important Disclaimer

Safe to Swim Hawaii is an independent passion project — it is not affiliated with the Hawaii Department of Health, any entity mentioned on this page, or any government agency or hotel brand. Water quality ratings on this site are estimates based on publicly available testing data and geographic analysis. They are not real-time measurements and may not reflect current conditions. “No DOH Alerts” means no advisory is currently posted — it does not mean the water was tested and found safe. DOH only monitors a fraction of Hawaii’s beaches, and some areas have no regular testing at all.

Always verify current water quality conditions with the Hawaii Department of Health Clean Water Branch before entering the water. This site is for informational purposes only and should not be the sole basis for any swimming decisions.

This site is a work in progress and we want to make it better. If you notice something that isn’t working right, have a suggestion, or want to share local knowledge about a beach, please reach out.

When in doubt, don’t go out. 🤙