Water quality, swimming safety, and what to know at Waikiki, Ala Moana, Fort DeRussy, Sans Souci, Kakaako, and Magic Island
Honolulu's beaches are unique in the world — a dense urban environment directly adjacent to the Pacific Ocean. That proximity to city infrastructure is both their greatest asset (convenience, facilities, hotels) and their biggest water quality challenge. Urban runoff from streets, parking lots, storm drains, and the Ala Wai Canal can affect water quality significantly, especially after rain. Knowing which beaches to choose — and when to stay out — matters here more than at any rural beach.
Honolulu is a city. Every rain event washes contaminants from roads, parking lots, and drainage systems into the ocean. The Ala Wai Canal — which drains much of urban Honolulu — regularly discharges bacteria-laden water near Waikiki after rain. Wait at least 72 hours after any significant rainfall before swimming at any Honolulu beach.
The most famous beach in Hawaiʻi. Waikiki is a calm, protected urban beach with generally moderate bacteria risk under normal dry-weather conditions. The protected water is ideal for casual swimming, outrigger canoe rides, and surf lessons. It's one of the most beginner-friendly ocean swimming spots in the world.
The main water quality concern is the Ala Wai Canal at the west end of the beach. After heavy rain, bacteria levels can spike dramatically, particularly near the Hilton Hawaiian Village end of Waikiki. The further east you go (toward Diamond Head), the better the water quality tends to be.
Ala Moana Beach Park is a large city park with a long sandy beach popular with local residents, lap swimmers, and families. The long, straight shoreline is good for swimming parallel to the beach. Water quality is moderate under normal conditions. The park is immediately adjacent to several storm drain outfalls, making it more vulnerable to post-rain contamination than more exposed beaches.
Note: Magic Island Lagoon sits at the eastern end of Ala Moana Beach Park but is a separate, enclosed lagoon with much worse water quality. Do not confuse the two — see the Magic Island section below.
Fort DeRussy Beach is a quieter stretch of Waikiki adjacent to the military recreation area. It has the same general water quality conditions as central Waikiki but tends to be less crowded since there are fewer hotels directly fronting it. A good option for those wanting to swim in Waikiki without the crowds. The same Ala Wai Canal concerns apply after rain.
Sans Souci (also called Kaimana Beach) is at the Diamond Head end of Waikiki near the New Otani Kaimana Beach Hotel. It tends to have better water quality than central Waikiki because it's farther from the Ala Wai Canal, has better tidal flushing from Diamond Head's position, and sees fewer visitors. A favorite with local swimmers and those who know to seek out the quieter end of the beach.
The park itself — the grassy lawns, picnic areas, and walking paths of Magic Island — is lovely and worth visiting. Just stay out of the lagoon water.
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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 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 clean.
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. If you notice something that isn't right or want to share local knowledge, please reach out.
When in doubt, don't go out. 🤙