The city's Ocean Safety and Lifeguard Services and Parks and Recreation Department said this morning that Hanauma Bay will be closed due to a high number of box jellyfish spotted on the beach and in the nearshore waters.

In less than an hour, more than 20 box jellyfish were found on the beach at Hanauma Bay this morning with countless more spotted floating just offshore, the city said in a news release.

More than 650 box jellyfish were also found on Waikiki Beach this morning but no stings have yet been reported.

Waikiki Beach remains open, but beach-goers are strongly urged to check with lifeguards before venturing into ocean waters.

"As expected, the monthly influx of box jellyfish arrived today and there has been a large number of the creatures found at Hanauma Bay and Waikiki Beach this morning," said Bryan Cheplic, spokesman for the Honolulu Emergency Services Department. "After discussing the situation with the city's Parks and Recreation Department the decision was made to close the bay effective at 7 a.m."

The situation will be re-assessed tomorrow morning and a decision will be made to keep Hanauma Bay closed or open it to the public.

Persons stung by box jellyfish are advised to flush the sting area with lots of white vinegar. Anyone experiencing breathing difficulty, muscle cramps or spasms, and/or persistent pain are advised to seek immediate medical attention. Lifeguard stations are supplied and equipped to treat this type of marine sting.