Hawaii Water Quality Rankings
Top-Rated Beaches by Water Quality in Hawaii
These rankings are based on water quality data, not aesthetics. We ranked beaches across all four major islands using DOH bacteria testing results, proximity to streams and runoff sources, historical advisory frequency, and geographic risk factors. The cleanest beaches share three traits: no stream outlets, dry leeward coasts, and strong ocean circulation.
How to Use These Rankings
These are historical water quality rankings, not current conditions. They reflect how beaches have performed over time based on bacteria testing data and geographic analysis. Any beach can have elevated bacteria after a rain event, regardless of its historical rating.
This page ranks beaches by water quality and bacteria data only. It does not rank drowning risk, wave danger, currents, or physical hazards. A beach with excellent water quality can still be dangerous for swimming due to shore break, rip currents, or rocky entries. Always check ocean conditions in addition to water quality.
Always check current conditions on Safe to Swim Hawaii or the DOH Clean Water Branch before swimming. Follow the 72-hour rule after rain regardless of historical ratings.
57
Beaches tested regularly by Hawaii DOH
250+
Total swimmable beaches — most never tested
130
CFU/100mL — enterococci threshold for advisory
88K
Cesspools statewide — #1 contamination source
What Makes a Beach Clean
The Three Factors Behind Clean Water
After analyzing years of DOH testing data and mapping every beach against streams, storm drains, and coastal geography, three factors consistently predict water quality.
1. No Stream Outlets or Storm Drains
Streams and storm drains are the primary pathway for bacteria to travel from land into the ocean. Beaches without nearby stream outlets receive dramatically less contamination after rain because there is simply no pipeline for runoff to reach them. This is the single biggest predictor of water quality. Beaches like Hapuna, Wailea, and Ko Olina have no stream outlets and consistently test clean.
2. Dry Leeward (South/West) Coast
Leeward coasts are sheltered from the trade winds by the island’s mountains and receive a fraction of the rainfall that windward coasts get. Less rain means less runoff, fewer brown water events, and lower baseline bacteria levels. The difference can be extreme — the Kohala Coast on the Big Island receives roughly 10 inches of rain per year, while Hilo on the windward side gets over 130 inches.
3. Strong Ocean Flushing
Open-ocean beaches with direct exposure to currents and wave action flush contamination much faster than enclosed bays, lagoon-style beaches, or areas protected by breakwaters. When contamination does occur, well-flushed beaches return to clean conditions in 1–2 days instead of 3–5 days. UV exposure from direct sunlight also helps kill bacteria in shallow water.
Oʻahu — Top 5 by Water Quality
Oʻahu has the most beaches, the most people, and the most infrastructure-related contamination sources. The cleanest options are on the west (leeward) side, away from the urban core and the Ala Wai Canal system.
1Ko Olina Lagoons · West Oʻahu
Top Rated
No stream outlets. Man-made lagoons flush via ocean channels. Dry leeward coast receives minimal rain. Recovers within 1 day after storms. Home to Aulani and Four Seasons — the resort infrastructure means excellent water management. Consistently among the cleanest swimming areas on Oʻahu.
2Hanauma Bay · Southeast Oʻahu
Top Rated
Protected marine reserve with limited daily visitors (requires reservation). No stream outlets feeding into the bay. Limited urban runoff due to surrounding nature preserve. The reef creates an enclosed swimming area with excellent water clarity for snorkeling. Bacteria counts historically very low.
3Lanikai Beach · Windward Oʻahu
Low Risk
Despite being on the windward side, Lanikai benefits from its position away from major stream outlets. The Mokulua Islands offshore create some wave protection. Water quality is generally excellent in dry weather but can be affected after heavy rain due to the nearby Kawainui Marsh drainage. Best during dry season or dry spells.
4Waikiki Beach (Diamond Head sections) · South Oʻahu
Moderate
The eastern sections of Waikiki closest to Diamond Head test cleaner than the western end near the Ala Wai Canal outflow. Strong ocean circulation and the south-facing orientation help. Bacteria levels spike after rain due to the Ala Wai Canal, but recover within 2–3 days at the Diamond Head end. The western end near the canal is more consistently affected.
5Waimanalo Beach · Windward Oʻahu
Low Risk
Long stretch of beach with limited stream influence at the main swimming areas. Less development means less urban runoff compared to Kailua to the north. Water quality is generally good, particularly during dry weather. The long, open beach has good ocean flushing. Affected after heavy windward rain but recovers within 2–3 days.
For detailed rankings: All Oʻahu Beach Rankings →
Maui — Top 5 by Water Quality
Maui’s south shore is the driest coast in the state, making South Maui beaches consistently the cleanest. West Maui is drier than windward but has more stream outlets.
1Wailea Beach · South Maui
Top Rated
Sits on the driest coast in Hawaii. Minimal stream influence, excellent ocean flushing, and strong UV exposure that kills bacteria. Recovers within 1 day after the rare rain event. Bacteria counts are among the lowest in the state across years of DOH testing. The resort development includes modern wastewater treatment, not cesspools.
2Makena Beach (Big Beach) · South Maui
Top Rated
South of Wailea with even less development and no stream outlets. The dry lava rock coastline means virtually zero runoff. Strong open-ocean flushing and full sun exposure. One of the cleanest large beaches in Hawaii. Note: the shore break here can be powerful — this ranking is for water quality only, not wave safety.
3Kapalua Bay · West Maui
Low Risk
Sheltered crescent bay with minimal direct stream input. While West Maui gets more rain than South Maui, Kapalua Bay’s position and limited runoff sources keep it consistently clean. Excellent snorkeling conditions. Bacteria counts have been low in DOH testing. Slightly slower to recover after rain than South Maui beaches due to the sheltered bay shape.
4Keawakapu Beach · South Maui
Low Risk
Between Kihei and Wailea on the dry south shore. Less crowded than Wailea with similar water quality advantages: dry coast, minimal streams, good ocean circulation. A local favorite that benefits from the same geographic factors that make South Maui the cleanest coast on the island.
5Napili Bay · West Maui
Low Risk
Small, calm bay just south of Kapalua with limited stream influence. The enclosed bay provides calm swimming conditions and the limited watershed above it means less runoff compared to other West Maui beaches. Generally tests well in DOH monitoring. Good option for families on the West Maui side.
For detailed rankings: All Maui Beach Rankings →
Kauaʻi — Top 5 by Water Quality
Kauaʻi is the wettest major island. The south shore (Poipu area) is the clear standout for water quality. The north shore has chronic issues from cesspools and high rainfall.
1Poipu Beach · South Kauaʻi
Top Rated
The dry south shore is Kauaʻi’s most reliable coast for water quality. No major stream outlets, minimal rainfall even during wet season, and strong ocean circulation. DOH testing consistently shows low bacteria counts. The natural rock breakwater creates a calm wading area for children while the open-ocean side flushes contamination efficiently. Recovers within 1–2 days after rain.
2Shipwreck Beach (Keoneloa) · South Kauaʻi
Low Risk
Adjacent to the Grand Hyatt on the dry south shore. Same geographic advantages as Poipu: dry coast, no stream outlets, strong ocean flushing. Less crowded than Poipu Beach. The shore break can be powerful, so this ranking reflects water quality not wave conditions. Excellent water clarity year-round.
3Anini Beach · North Kauaʻi
Moderate
Protected by one of the longest fringing reefs in Hawaii, creating a calm lagoon. While on the wetter north shore, Anini’s reef provides some filtration and the beach is positioned away from the worst stream outlets that plague Hanalei. Good in dry weather but affected after significant north shore rain. Better water quality than nearby Hanalei.
4Lydgate Beach Park · East Kauaʻi
Moderate
Rock-walled swimming pools provide calm, enclosed swimming. While on the windward east side near the Wailua River, the man-made pools have some degree of separation from direct river runoff. A popular family beach with generally acceptable conditions during dry weather. Avoid after rain due to the Wailua River proximity.
5Salt Pond Beach Park · West Kauaʻi
Low Risk
On the dry west side of Kauaʻi near Hanapepe. Protected reef creates calm swimming conditions. Low rainfall area with minimal stream influence. Less visited than south shore beaches, which means less contamination from heavy foot traffic. Consistently good water quality in DOH testing.
For detailed rankings: All Kauaʻi Beach Rankings →
Big Island — Top 5 by Water Quality
The Big Island’s Kona and Kohala Coast is the most consistently clean coastline in the state. The dry western shore has minimal streams, receives little rainfall, and benefits from the rain shadow of Mauna Kea and Mauna Loa.
1Hapuna Beach · Kohala Coast
Top Rated
Widely regarded as having some of the cleanest water in Hawaii. The Kohala Coast receives roughly 10 inches of rain per year. No stream outlets, strong open-ocean flushing, full sun exposure, and minimal development. Bacteria counts are consistently among the lowest in DOH testing statewide. Recovers within 1 day after the rare rain event. Large, well-maintained state beach park.
2Kua Bay (Maniniʻowali) · North Kona
Top Rated
Tucked into a lava rock coastline with zero runoff sources. The surrounding lava fields mean no soil, no streams, no agricultural runoff, and no cesspools anywhere near the water. One of the most pristine swimming environments in the state. Clear turquoise water year-round. The lava rock entry can be rough on feet — water shoes recommended.
3Mauna Kea Beach (Kaunaʻoa) · Kohala Coast
Top Rated
Crescent-shaped white sand beach on the dry Kohala Coast. Same geographic advantages as Hapuna: no streams, minimal rainfall, excellent ocean flushing. The Mauna Kea Beach Hotel resort has modern wastewater infrastructure, not cesspools. Limited public parking keeps crowds manageable. Consistently excellent water quality.
4"A-Bay" (Anaehoomalu) · Kohala Coast
Low Risk
Protected bay on the Kohala Coast in front of the Waikoloa Beach Marriott. While the bay is more enclosed than Hapuna, its position on the dry coast means minimal runoff. The adjacent fishponds are separate from the swimming area. Good snorkeling conditions with consistently clean water. Slightly slower to flush than open-coast beaches but rarely affected by runoff.
5Spencer Beach Park · Kohala Coast
Low Risk
Reef-protected beach just south of Hapuna on the Kohala Coast. Calm, shallow water makes it excellent for families and children. Same dry coast location means minimal runoff and low bacteria counts. The reef provides protection from waves while still allowing enough water exchange to maintain quality. Well-maintained county beach park with full facilities.
For detailed rankings: All Big Island Beach Rankings →
Beaches with Chronic Water Quality Issues
Know Before You Go
These beaches have documented, recurring water quality problems. This does not mean you can never swim at them — many are beloved beaches with excellent conditions during dry weather. But they deserve extra caution, especially after rain.
Has failed bacteria tests consistently since 2016. Located near the Nawiliwili Harbor and multiple stream outlets. The enclosed bay shape traps contamination. Despite being a popular resort beach, the water quality data consistently exceeds advisory thresholds.
On the DOH impaired waters list since 2004. Four streams drain into the bay, and over 360 cesspools in the watershed discharge undertreated sewage. Extremely high rainfall on the north shore compounds the problem. Beautiful beach with chronic contamination from a structural cesspool problem that will take years to resolve.
Near Kaʻanapali with worsening bacteria trends. Multiple stream outlets along the West Maui coast feed runoff directly to the beach. Has shown bacteria levels exceeding 10x the advisory threshold during testing in early 2026. The contamination pattern suggests an ongoing source, not just storm-related spikes.
Popular snorkeling beach with a confirmed cesspool contamination plume. Despite being on the dry Kona coast, the concentration of cesspools in the immediate area creates chronic contamination that worsens after rain. The reef and marine life are excellent, but the water quality data shows persistent issues from the cesspool plume entering the bay.
For the full list, see our Worst Beaches for Bacteria guide.
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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. These rankings reflect historical water quality patterns based on publicly available DOH bacteria testing data and geographic analysis. They are not real-time measurements and do not guarantee current conditions. Any beach can have elevated bacteria levels after rain regardless of its historical rating. “No DOH Alerts” means no advisory is currently posted — it does not mean the water was tested and found safe.
Always verify current water quality conditions with the Hawaii Department of Health Clean Water Branch before entering the water.
When in doubt, don’t go out.