A huge influx of jellyfish, some the size of a dinner plate, is causing problems for North Island beaches.
Mount Maunganui first reported the problem, but now beaches all along the Coromandel coast are becoming infested.
Bay of Plenty Surf Lifesaving chief executive Megan Cleverley says at some beaches almost 30 people a day are needing treatment.
About four varieties of jellyfish have been identified.
Ms Cleverley says the jellyfish seem to be moving with the warmer waters but have not yet reached Tauranga.
So far, only one person has had a severe reaction after being stung.
At Mount Maunganui, lifeguards have been treating up to 10 people a day for stings.
Patrol captain Mike Copping says the sting is not dangerous in most cases. He says it is easily treated by washing off the jellyfish in sea water, then sluicing the sting with vinegar or warm water.
However, he says people should seek medical help immediately if they notice breathing difficulties or swelling around the throat.
The National Aquarium in Napier says it is the biggest swarm in years. But manager Rob Yarrell says this is jellyfish season, so their presence is not unusual.