About 350 children, aged 2 to 6, took part in the mini-triathlon which involved a run, cycle and waterslide to the finish.
Mrs Maclennan said there were not many events for children that age, and the triathlon was a way to include them in the community.
Event organiser Kerry Maclennan said the waterslide, run by Fire and Emergency New Zealand, was a hit with the youngsters.
"It was the highlight of the whole event,’’ she said.
"They see their older brothers and sisters involved in lots of different things ... this is a day for them.’’
Kelly Sport staff member Sophie Russell, who helped run the day, said the event had been fun and exciting for all involved.
"The Dunedin rain held off thankfully ... there has been nothing but smiles.’’