The wettest Hawaiian island — more brown water advisories than anywhere else. Live status, bacteria data, and safety ratings for every Kauaʻi beach.
Kauaʻi has the steepest rainfall gradient in Hawaii. The South Shore (Poʻipu, Brennecke) sits in the rain shadow and runs the cleanest. North Shore (Hanalei Bay, Anini, Tunnels) catches runoff from Mount Waiʻaleʻale (450+ inches of rain/year) through perennial streams — advisory-frequent especially in wet season. East Shore (Kalapaki, Lydgate) intermediate. Live DOH status for every Kauaʻi beach is in the module below.
Kauaʻi is the wettest of the main Hawaiian islands. Mt. Waiʻaleʻale near the center of the island averages over 450 inches of rain per year, making it one of the wettest spots on Earth. All that rain means more runoff, more stream discharge, and more brown water advisories than any other island in the state.
The south shore (Poipu) sits in the rain shadow and is the driest, sunniest part of the island — and generally the calmest for swimming. The north shore (Hanalei) is stunning but has chronic contamination from cesspools and multiple stream discharges. Kalapaki Beach near Lihue has the worst bacteria record in the entire state — 100% test failure since 2016.
If you're visiting Kauaʻi and water quality matters to you, stay on the south shore. If it's been raining, even Poipu deserves caution — but it recovers faster than anywhere else on the island.
Exploring Kauaʻi? These top-rated tours and activities pair perfectly with a beach day. Check water quality above, then plan your trip.
Tours listed via Viator and GetYourGuide. Safe to Swim Hawaii may earn a commission if you book, at no extra cost to you.
Beach water quality reports for popular Kauaʻi hotels — check conditions at your resort.
DOH only tests roughly 47 stations across the four main islands. Surfrider Foundation’s volunteer Blue Water Task Force adds 100+ community-tested sites on Oʻahu, Maui, and Kauaʻi. Molokaʻi and Lānaʻi still have no routine bacteria-testing program, so we separate that gap clearly.
Free alerts when water quality changes at your beach — brown water advisories, bacteria warnings, and all-clear notices.
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100+ beaches and 25+ hotels across all 6 islands
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — it is not affiliated with the Hawaii Department of Health or any government agency. 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.
This site does not recommend or advise anyone to swim at any beach. We share government data and geographic analysis so you can make your own informed decisions. By using this site you accept full responsibility for your own safety. See our Terms of Use for full details.
When in doubt, don't go out. 🤙