Kailua-Kona town, Kahaluʻuʻs bacteria problem, Magic Sands, and the Keauhou area.
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. Konaʻs coast is dry, but Kahaluʻu Bay has chronic bacteria contamination from freshwater springs carrying cesspool waste through porous lava rock. The 72-hour rain rule is especially important here.
Kailua-Kona is the main tourist town on the Big Islandʻs dry western coast. Aliʻi Drive runs along the waterfront for about 6 miles from the town center south to Keauhou. Unlike Waikikiʻs continuous sand beach, Konaʻs coast is mostly rocky lava shoreline with small beach pockets.
Important: "Kailua-Kona" is NOT the same as "Kailua" on Oʻahu. They are on different islands. Read our disambiguation guide →
Kahaluʻu is Konaʻs most popular snorkeling beach. Shallow reef, abundant sea turtles, easy entry. But it has a 92% bacteria test failure rate — one of the worst in Hawaiʻi. Freshwater springs discharge cesspool-contaminated water through the lava rock into the bay. This is a chronic, geological condition, not weather-dependent. If you snorkel here, avoid swallowing water, cover any open cuts, and shower with soap immediately after.
Known as "Magic Sands" because the sand disappears during high surf, exposing the rocky bottom, then returns when waves calm. Small beach with bodyboarding and bodysurfing. Water quality is generally better than Kahaluʻu because it has more open-ocean exposure and flushing. Lifeguard on duty.
Hotels: Sheraton Kona Resort & Spa, Outrigger Kona Resort
Keauhou Bay is primarily a boat harbor for manta ray night snorkel/dive tours. The Sheraton has a manta ray viewing area where mantas come nightly to feed on plankton attracted by spotlights. Limited beach swimming in this area — itʻs more about boat-based activities.
Konaʻs coast is generally dry, but the water quality picture is complicated by submarine groundwater discharge. Cold freshwater flows through the porous basalt lava from the slopes of Hualalai and Mauna Loa, carrying bacteria from the estimated 50,000+ cesspools in West Hawaiʻi. This freshwater emerges as springs along the coast, particularly at Kahaluʻu. Beaches with more open-ocean exposure (like Magic Sands) flush better than enclosed bays (like Kahaluʻu).
Top-rated experiences in the area.
Tours via Viator and GetYourGuide. We may earn a commission at no extra cost to you.
Free alerts when water quality changes.
No spam. Just safety alerts.
100+ beaches across all islands
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with the Hawaii Department of Health or any government agency. Water quality ratings 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 DOH Clean Water Branch before entering the water.
When in doubt, don't go out. 🤙