Water quality ratings and safety guide for the Big Island's hidden south coast beaches
📍 Hōnaunau, Hō'okena, Miloli'i — South Kona, Hawaiʻi Island
South Kona is one of the Big Island's most rewarding coastlines for independent explorers. Unlike the resort-heavy Kohala Coast, South Kona beaches feel wild and authentic — a mix of traditional fishing villages, ancient Hawaiian sites, and world-class snorkeling in crystal-clear water. Water quality here is generally good thanks to the dry leeward climate and minimal urban development.
Two Step is a lava ledge entry point to pristine open ocean. Named for the two-step lava formation used to enter the water, this spot offers exceptional snorkeling with spinner dolphins, sea turtles, and abundant reef fish. Water quality is outstanding — open ocean, lava bottom, minimal runoff. One of the best snorkel spots on the Big Island.
Full guide →Hō'okena Beach Park has a distinctive gray sand beach in a small, sheltered bay. There are restrooms, camping, and kayak rentals. The bay provides some shelter from wind and waves making it one of the more swimmable South Kona beaches. Spinner dolphins frequently visit. Water quality is good but the stream and camping activity add a slight risk factor.
Full guide →Miloliʻi is one of the last traditional Hawaiian fishing villages in Hawaiʻi. The beach is rocky with a small sandy section and a protected swimming area. Water quality historically rates at low bacteria levels — minimal development and steady ocean flushing. The village is an active community; respect local customs and private property. Excellent for snorkeling in the sheltered area.
Full guide →Kealakekua Bay is a State Marine Life Conservation District with some of the clearest, most biodiverse water on the Big Island. The Captain Cook Monument (Kaʻawaloa) on the north shore is reached by kayak or tour boat. Snorkeling here is world-class. Water quality historically rates at low bacteria levels. Kayak tours depart from the south end at Napoʻopoʻo Beach.
Keʻei is a small sheltered beach in a residential area near Kealakekua Bay. The protected cove makes for calm water but limited flushing. Some runoff from nearby homes adds a moderate bacteria risk. Good for tidepooling and calm-water snorkeling, but not the best choice if recent rain has occurred.
South Kona is drier than east Hawaiʻi, but volcanic activity and upslope rain can still send runoff to the coast. Wait at least 72 hours after heavy rain before swimming, especially near stream mouths or in sheltered bays with limited circulation.
Top-rated experiences near this beach. Check water quality above, then plan your trip.
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Hawaii’s Department of Health monitors approximately 57 beaches statewide through regular bacteria testing. However, with over 300 swimmable beaches across the islands, many popular spots have no regular testing program. Water quality varies significantly based on rainfall, stream proximity, coastal development, and ocean circulation patterns.
After heavy rain, streams and storm drains carry bacteria, sewage, pesticides, and sediment into coastal waters. The DOH recommends staying out of the ocean for at least 48 to 72 hours after heavy rain, even if the water appears clear. Brown or murky water is a visible sign of contamination, but bacteria can be present in clear water near stream mouths.
This site aggregates data from six sources — DOH advisories, USGS stream monitoring (25 stations), NOAA tide and temperature data, NDBC wave buoys, NWS weather alerts, and City & County of Honolulu water testing — to provide a more complete picture than any single source.
The 72-hour rule is the standard guideline from the Hawaii Department of Health: avoid swimming for at least 72 hours after heavy rain stops, especially near stream mouths, canal outlets, and areas with brown or discolored water. This applies to all beaches across all islands.
Bacteria from urban runoff, agricultural land, and aging cesspool systems enters the ocean through streams and storm drains. Hawaii has approximately 88,000 cesspools — more than any other state — many of which leak untreated sewage into groundwater that eventually reaches the coast. Beaches near known cesspool contamination areas carry higher risk, particularly after rainfall.
Safe to Swim Hawaii aggregates water quality data from six independent sources to provide broader coverage than any single agency. Our sources include the Hawaii Department of Health Clean Water Branch (beach advisories and bacteria testing), USGS National Water Information System (25 stream monitoring stations across all islands), NOAA CO-OPS (tide levels and water temperature), NDBC (wave buoys and ocean conditions), NWS Honolulu (weather and marine alerts), and City & County of Honolulu Environmental Services (Kailua Bay water testing and spill reports).
Historical bacteria risk ratings on this site are based on DOH testing data, Surfrider Foundation monitoring, geographic analysis (stream proximity, cesspool contamination areas, coastal development), and advisory frequency. These are historical assessments, not live measurements. Always check the live advisory status at the top of each page and verify conditions with the Hawaii DOH Clean Water Branch before entering the water.
⚠️ 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.
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. 🤙