4 islands compared with data-backed recommendations
| Island | Score | Top Beach |
|---|---|---|
| Oʻahu | 5/10 |
— |
| Maui | 7/10 |
Kapalua Bay |
| Big Island | 8/10 |
Kona Coast beaches |
| Kauaʻi | 6/10 |
Poipu Beach |
Top beach: Kona Coast beaches
Why: Volcanic rock filtration produces clean ocean water on the Kona coast. Our data shows consistently low bacteria levels at Kua Bay and A-Bay.
Caveat: Kahaluʻu Beach has a 92% bacteria failure rate — not all Big Island beaches are clean
Top beach: Kapalua Bay
South and West Maui consistently pass DOH water quality tests
Ala Wai Canal runoff contaminates Waikiki after rain. Multiple North Shore beaches have chronic advisories (April 2026 data).
Based on our analysis, Big Island is the top pick for water quality in Hawaii. Volcanic rock filtration produces clean ocean water on the Kona coast. Our data shows consistently low bacteria levels at Kua Bay and A-Bay.. The top beach for this is Kona Coast beaches.
Big Island is generally good for water quality throughout the year, though conditions vary by season. Kahaluʻu Beach has a 92% bacteria failure rate — not all Big Island beaches are clean
While all four main islands offer some version of this experience, the quality varies significantly. Oʻahu is the weakest option because: Ala Wai Canal runoff contaminates Waikiki after rain. Multiple North Shore beaches have chronic advisories (April 2026 data).
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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.
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.
When in doubt, donʻt go out. 🤙