More than 200 people were stung by box jellyfish at Waikiki and Ala Moana beaches over the last two days, and lifeguards are urging people to stay out of south shore waters to avoid the painful welts.

"They’re inundating the beaches," said Capt. Paul Merino, supervisor of Ocean Safety and Lifeguard Services for the south shore. "The lifeguards are just overwhelmed."

Box jellyfish, nearly invisible in the water, leave a painful sting that can be dangerous for people who are allergic. One beachgoer was sent to the hospital yesterday for treatment of anaphylactic shock, followed by two more this morning, Merino said. 

The influx began yesterday and is expected to last through New Year’s Day and begin to fade on Sunday, he said. Warning signs went up along south shore beaches yesterday.

"Being that it’s such a nice day, people aren’t heeding the warnings," Merino said. "It’s a perfect storm. It was rainy all week, and now it’s sunny and beautiful today, and jellyfish are on the beach."

Box jellyfish typically measure one to two inches long, with tentacles that stretch about a foot long. Lifeguards advise beachgoers to immerse the sting in warm water, or try a cold pack to relieve the pain.