There were squeals as people braved the cold waters of Lake Tikitapu (Blue Lake) for Dunk for Harold.
The event was held this morning as a fundraiser for Life Education Trust Rotorua.
Life Education Trust Rotorua trustee Kylie Brackfield said it was a smaller crowd this year but more money had been raised.
"All the dunkers that have come have been hand on heart."
She said the Rotorua business community had been generous with prizes and a prize wheel had been donated to them by Westbrook School.
Ms Brackfield said they were pleased with the result and some people's Givealittle pages did not finish until later tonight.
"The hard work was definitely worth it. The atmosphere out here has been really great, it was excellent.
"It's a relief to see it's been a success."
She said there were 45 dedicated dunkers and more than $4000 had already been raised, with more funds still to come in.
They had been running Dunk for Harold for more than 10 years, she said.
The event also included rocks children could decorate - some of which had spot prizes under them - a sausage sizzle and raffles.
A $2000 travel voucher was up for grabs and for every $100 a participant raised they got an entry in the draw.
Ms Brackfield said the event was about having fun in the community and raising their profile.
She said Life Education Trust Rotorua saw 6000 children a year, which was a big commitment and they had to find the funds to keep running it.
Dunker Julie Voss, who took part in a submarine costume, said she had been nervous beforehand because she could hardly see.
She said it was a lot colder than she was expecting in the water.
"It was great fun."
She said Life Education Trust Rotorua was a great cause to get behind because it supported children and went to all schools, teaching them about who they were, being healthy and being confident.
Kade Brackfield, 5, said he was excited when he jumped in the lake and it was freezing.
He said he also took part last year when he had been dressed up as Woody.
Sierra Harris, 11, said this was her second time doing it and her favourite part had been dressing up in a crazy costume with her friends.
She and her two friends had raised $600.
She said it was an important event to get behind so that Harold could keep going to schools and talking about Life Education.