JAMM AQUINO / JAQUINO@STARBULLETIN.COM Box jellyfish warning signs were posted yesterday afternoon at Kuhio Beach in Waikiki.

Jellyfish swarm off Oahu shores

The third-largest influx since 1997 stings at least 235 beachgoers

After a morning hike up the Diamond Head trail yesterday, 9-year-old Jason Kerr was looking forward to cooling off in the ocean.

But less than 15 minutes after he entered the Waikiki waters with his boogie board, a box jellyfish ruined his plans.

"At first, I didn't know it stung me. But then it (my leg) started hurting and itching, so I got out of the water," he said yesterday.

JAMM AQUINO / JAQUINO@STARBULLETIN.COM Daniel Lyngcoln of North Queensland, Australia, was stung above his left collarbone and shoulder while swimming in waist-deep water with his girlfriend at Kuhio Beach.

More than a thousand of the creatures around the island stung at least 235 people, including four who went to the hospital, said Bryan Cheplic, a Honolulu Emergency Services Department spokesman.

He said jellyfish were reported along the South and West shores, and the invasion forced officials to close Hanauma Bay at about 11 a.m.

Although Ocean Safety officials expected the jellyfish invasion Wednesday, the reports started rolling in as early as 12:45 a.m. yesterday, long before lifeguards arrived at their posts.

At about 9 a.m., Ocean Safety Division officials issued a warning, advising people to stay out of the water. Waikiki lifeguards also posted warning signs along the beach.

"I saw the signs, but I looked around and it didn't seem to bother anyone else here," Kerr's mother, Kristyn, said. She was among the many beachgoers who did not notice or heed the warnings.

"Many of them are tourists and don't necessarily know what they (jellyfish) are or what they can do," Cheplic said.

The effects can include minor skin irritation, difficulty breathing, muscle cramps or spasms and anaphylactic shock.

A 17-year-old girl was taken in serious condition from Waikiki to the Queen's Medical Center, and a 4-year-old girl taken in stable condition from Ko Olina to St. Francis West Medical Center. Both suffered allergic reactions to the stings.

Although lifeguards and paramedics treated hundreds in the morning, the reports tapered off by the afternoon.

"The jellyfish are really sensitive to sunlight, so they go deeper in the water later in the afternoon and we see less reports of stings," Cheplic said.

Lifeguards said they did not notice a huge drop in the number of people enjoying Waikiki's beach, but businesses did.

Paulo De Azevedo, a surf instructor for Star Beach Boys, said his company had only about half its normal amount of customers.

Jellyfish appear about 10 days after a full moon, usually in Waikiki, so Ocean Safety officials expect fewer of the creatures in the waters today.

Kerr's father, Ken, said his son's sting did not alter their plans to play in the water and visit the beach every day: "He's tough, so he'll go back in and brave it."