Box jellyfish: when they show up and what to do

Box jellyfish tend to wash in about 8 to 10 days after each full moon, mostly on south- and west-facing (leeward) shores such as Waikīkī, Ala Moana and Salt Pond on Kauaʻi. Lifeguards post warning signs on those days.

• Timing: sightings usually rise about 8 to 10 days after the full moon, every month.
• Where: mostly leeward, south- and west-facing beaches. Examples where warning signs have been posted include Waikīkī and Ala Moana on Oʻahu and Salt Pond Beach Park on Kauaʻi.
• Before you swim: look for yellow box jellyfish signs and ask the lifeguard.
• If you are stung: get out of the water, tell a lifeguard, and call 911 if the person has trouble breathing, chest pain or a strong allergic reaction.
• Daily conditions and warnings are on Hawaiʻi Beach Safety.

Sources: Hawaiʻi Beach Safety (lifeguard warnings) · County of Kauaʻi: Box jellyfish signs at Salt Pond · Hawaii News Now: Box jellyfish advisory for Waikīkī

Last checked Oct. 29, 2026. Hours, fees and rules can change, so confirm with the official source before you go.