Ko Olina lagoon water quality & swimming guide
📍 Ko Olina, Kapolei, Oʻahu — Protected lagoon swimming
Ko Olina Lagoon 4, fronting the Four Seasons, benefits from Oʻahu’s dry leeward coast and the lagoon’s engineered water circulation system. With no streams, no agriculture, and constant ocean water exchange through channel openings, bacteria risk is consistently very low.
The Ko Olina lagoons have matured significantly since construction and now support healthy coral growth, reef fish, sea turtles, and the occasional Hawaiian monk seal visit. The Four Seasons is positioned on the most private and least-trafficked of the four lagoons.
Ko Olina is on Oʻahu’s dry leeward side and rarely receives heavy rain. On the rare occasions when significant rainfall occurs, wait 72 hours before swimming. The lagoons flush quickly due to their circulation design.
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⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with the Hawaii Department of Health or Four Seasons Hotels. Water quality ratings are estimates based on historical data and are not real-time measurements.
Always verify with the Hawaii Department of Health Clean Water Branch before swimming.
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. 🤙