Event organiser Isaac Smith, from Sport Otago, said the turnout was "fantastic".
"Dunedin put on a great day for it.
"It was great to see all the families getting out, getting active, and having some fun together."
The annual triathlon involves a run, cycle and water slide to finish, but Mr Smith said the slide was once again the highlight.
But it was not only the children enjoying it, he said.
"I think the kids, and the staff, all seemed to have a lot of fun on the slide."
The Stride, Ride and Slide will be held in Oamaru on Saturday and in Balclutha on Sunday.