Ko Olina, Electric Beach, Makaha, and the leeward coast — water quality, swimming, and what to know
Ko Olina Lagoons
4 man-made lagoons. Calm, protected, family-perfect. Resort area.
Kahe Point (Electric Beach)
Top snorkeling spot. Spinner dolphins. Rocky entry — no lifeguard.
Nanakuli Beach Park
Local beach park. Camping. Shallow sandy entry. Good for families.
Maʻili Beach Park
Long sandy beach, bodysurfing, community park. Occasional shore break.
Makaha Beach Park
Legendary surf beach. Historic big-wave site. Dangerous in winter.
Keawaʻula (Yokohama Bay)
Remote, scenic, powerful shore break. Experienced swimmers only.
West Oʻahu (the leeward coast) is in the rain shadow of the Koʻolau and Waiʻanae Mountains. This side of the island receives significantly less rainfall than Honolulu or the windward coast — meaning less runoff, less river discharge, and consistently better water quality.
Ko Olina and most leeward beaches consistently score Low Risk (1/5) on Hawaii DOH bacteria testing. Even after heavy statewide rain, the leeward coast usually recovers faster. The 72-hour rule still applies after any significant rainfall.
Ko Olina's four man-made lagoons are the calmest swimming spots on the entire west Oahu coast. Built in the 1990s as part of the Ko Olina resort development, each lagoon is partially enclosed by a rock seawall that blocks ocean swells — creating calm, clear, waist-to-shoulder-deep swimming areas that feel like a protected bay.
All lagoons have public access rights — parking lots can fill early on weekends. No lifeguards at any lagoon.
Kahe Point Beach Park — nicknamed Electric Beach — is west Oahu's hidden gem for snorkelers and divers. The Hawaiian Electric plant adjacent to the beach discharges warm, filtered seawater that creates an unusual microhabitat: exceptionally clear water with abundant marine life.
Spinner dolphins rest in the calm bays near Kahe Point on most mornings. Sea turtles are almost guaranteed. The warm discharge plume attracts fish, creating one of Oahu's richest dive sites just offshore.
Makaha Beach was one of the first big-wave surf sites in Hawaii — home to the Makaha International Surfing Championship (1954–1971). The beach is beautiful, but the ocean here is powerful. In summer it can be calm enough for swimming and boogie boarding. In winter (October–April), Makaha receives large northwest swells and is for expert surfers only.
Yokohama Bay (Keaʻwaʻula) at the end of the road in Waiʻanae is remote and dramatic. The shore break is almost always present. Swim only when conditions are clearly flat and calm.
Top-rated experiences near this beach. Check water quality above, then plan your trip.
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Free alerts when advisories change at your beach.
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.
Independent passion project — not affiliated with Hawaii DOH. Ratings not real-time. Verify with Hawaii DOH.
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. 🤙
⚠️ 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. 🤙