Box jellyfish made a rare appearance in force off Leeward O'ahu beaches yesterday on the second day of the creatures' monthly influx.

Lifeguards yesterday morning counted about 700 jellyfish along the Wai'anae Coast, and 30 people reported being stung there, including 20 people on a dolphin dive tour who were stung as they surfaced into a field of jellyfish, said Bryan Cheplic, spokesman for the city Emergency Services Department.

No one required medical attention, he said.

"They haven't seen those numbers on the west side in 10 years," Cheplic said. "That's a lot for the west side, and we are advising people to stay out of the water."

On a typical month, Cheplic noted, fewer than a dozen jellyfish are found on Leeward beaches during influx periods, which occur about 10 days after a full moon.

Jellyfish are more likely to frequent Waikiki, particularly in the area 'ewa of the Kapahulu groin. Yesterday 297 jellyfish were counted and 20 people stung in Waikiki, compared with 122 and 35, respectively, on Monday.

Anyone who is stung and experiences difficulty breathing, muscle cramps or spasms or persistent pain should seek immediate medical attention.

For the latest information about ocean conditions, advisories and warnings, call the city's recorded report at 922-3888 or visit http://oceansafety.soest.hawaii.edu.