Is it safe to swim in O'ahu today?

Check the live status at the top of this page for current O'ahu advisories, updated every 15 minutes. The Hawaii Department of Health issues brown water advisories and beach advisories when bacteria levels exceed safe thresholds. Water quality on O'ahu is affected by recent rainfall, the Ala Wai Canal (the single largest contamination source on the south shore), stream runoff from the Ko'olau Mountains on the windward side, and urban stormwater discharge. After heavy rain, avoid swimming for at least 72 hours, especially near stream mouths and canal outlets.

Which O'ahu beaches have the cleanest water?

The cleanest beaches on O'ahu are generally the Ko Olina lagoons (enclosed man-made lagoons on the dry leeward coast with minimal stream exposure), Hanauma Bay (a protected marine reserve with restricted access and no nearby stream outlets), and beaches on the dry west and leeward coast away from stream mouths. These areas receive less rainfall and have fewer contamination sources compared to the south shore and windward side.

Which O'ahu beaches are most contaminated?

The most contamination-prone beaches on O'ahu include Ala Moana Beach Park (directly affected by Ala Wai Canal discharge and Kewalo Basin harbor runoff), Kailua Beach after rain (Kawainui Marsh drainage carries bacteria and sediment), and Waikiki Beach during brown water advisory events when the Ala Wai Canal overflows. The Ala Wai Canal carries urban runoff, sewage overflow, and debris from a 19-square-mile watershed directly to the ocean near Waikiki.

Is Waikiki Beach safe to swim today?

Waikiki Beach is generally safe for swimming in dry weather conditions. However, risk increases significantly after rain due to the Ala Wai Canal, which runs directly behind Waikiki and discharges contaminated urban runoff into the nearshore waters. During brown water advisory events, bacteria levels near Waikiki can spike well above safe swimming thresholds. Check the live status at the top of this page for current advisory status, and avoid swimming for at least 72 hours after heavy rain.

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LIVE STATUS · OʻAHU

Oʻahu Beach Water Quality Today

Live advisories for Waikiki, Kailua, North Shore, and all Oʻahu beaches — updated every 15 minutes

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Oʻahu Water Quality Overview

Oʻahu is home to roughly 84% of Hawaii's hotel rooms, meaning most visitors swim on this island's beaches. Water quality varies dramatically depending on where you are and when it last rained.

The Ala Wai Canal is the single largest contamination source on Oʻahu's south shore. It drains a 19-square-mile urban watershed — carrying sewage overflows, storm runoff, motor oil, and trash — and discharges directly into the ocean between Waikiki and Ala Moana. After any significant rain, bacteria levels near its outlet spike well above safe swimming thresholds.

The windward coast (Kailua, Lanikai) receives more rainfall and has marshland drainage that elevates bacteria after storms. The leeward and west side (Ko Olina, Makaha) is drier with fewer stream mouths, generally resulting in cleaner water. The North Shore has seasonal surf that stirs up sediment plus multiple stream outlets that carry runoff during winter rains.

South Shore Beaches

Waikiki Beach · Ala Wai Canal proximity

Moderate

Ala Moana Beach Park · Canal & harbor runoff

Elevated

Hanauma Bay · Protected marine reserve

Low

Diamond Head Beach · Rocky shoreline, tide pools

Low

East Side

Sandy Beach · Powerful shorebreak

Moderate-Low