Rip currents, shore break, jellyfish, sunscreen, beach flags — everything you need to stay safe in Hawaiian waters
Rip currents are powerful, channeled flows of water that move rapidly away from shore. They form when water pushed toward the beach by waves funnels back through a narrow gap — often at a break in a reef, near a pier, or through a low point in a sandbar.
How to spot one: Look for choppy, discolored water moving perpendicular to shore. Foam, seaweed, or debris moving steadily seaward. A gap in the breaking wave pattern.
How to escape: Don't fight it by swimming straight to shore. Swim parallel to the beach until you're out of the current, then angle back in. If you can't swim out, float and wave for help.
High-risk beaches: Hanauma Bay's channel, Waimea Bay, Makapūʻu, Sunset Beach, many South Shore beaches during south swell.
Shore break happens when waves break directly on the beach slope rather than peaking offshore. In Hawaii, shore break can be extremely heavy — even a 3-foot shore break wave can knock you off your feet, tumble you, and slam you face-first into hard-packed sand.
Sandy Beach on Oʻahu is the most dangerous shore break beach in the state and has one of the highest spinal injury rates of any beach in the U.S. Makapūʻu and Kealia on Kauaʻi are also known for severe shore break.
Box jellyfish are the more serious threat. They arrive in predictable cycles — typically 8 to 10 days after each full moon — on South-facing shores like Waikiki, Ala Moana, and Hanauma Bay. Invasions typically last 2 to 3 days. Their sting is painful and in rare cases can cause severe reactions.
Portuguese man-o-war (often mistakenly called bluebottle jellyfish) appear when northeast trade winds shift or die, washing them onto windward and north-facing beaches. Their long tentacles can sting even when washed ashore.
Treatment: Rinse with seawater (not fresh water), remove tentacles with a card — not bare hands. For box jellyfish, apply vinegar or heat. Seek medical attention for severe reactions, difficulty breathing, or stings covering large areas.
Check our Hawaii jellyfish calendar for the monthly box jellyfish forecast.
Hawaii banned the sale of sunscreens containing oxybenzone and octinoxate in 2021 because these chemicals damage coral reefs. Use mineral sunscreen with zinc oxide or titanium dioxide — it's better for the reef and you can find it at any drugstore or grocery on the islands.
At the latitude of Hawaii, UV index frequently hits 10 to 11+ in summer. The sun is intense year-round. Wear a rash guard in the water, reapply every 80 minutes, and cover up between 10am and 2pm when possible.
UPF-rated rash guards and water shirts offer better protection than sunscreen in the water and don't wash off. They're standard gear for local kids and worth the investment for any family visit.
Not all Hawaii beaches have lifeguards. Many remote beaches — and some popular ones — are unguarded. If there's no lifeguard tower, exercise extra caution. On Oʻahu, the City & County of Honolulu operates most guarded beaches. Maui County, Kauaʻi County, and Hawaii County each run their own programs.
Read more: Hawaii Beach Flags — Full Guide
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⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with any government agency. Water quality ratings are estimates based on publicly available data and are not real-time measurements.
Always verify conditions with the Hawaii DOH Clean Water Branch before entering the water.
When in doubt, don't go out. 🤙