Mum, Dad and Nana will be cheering from the sideline this Sunday as 300 little athletes are set to run, swim, and cycle the Pahoia School triathlon at Omokoroa's waterfront.

The triathlon is tomorrow, and organiser Kim McCormack says the whole family is set to turn up to cheer on their participant.

'You usually get Mum and Dad, and Nana might come, so there's usually hundreds of supporters.”

The triathlon has a focus on having fun and getting outside, which is exactly what Kim wants to see.

There are separate races for boys and girls in each age-group, five and six-year-olds swim/splash 25m, bike 400m and run 200m.

Seven and eight-year-olds swim 50m, bike 800m and run 750m, while nine and 10-year-olds swim 75m, bike 1.4km and run 1.2km. And those aged 11-13 swim 100m, bike 2.8km and run 1.6km.

'We just want all the kids to have a go. The emphasis is on the ‘try'athlon, rather than the competition.”

In its sixth year, the triathlon is held down by the water at Omokoroa's Crapp Reserve – and plans are full steam ahead despite forecasted rain tomorrow, though route changes may be made.

'Depending on how heavy the rain is, the course might be modified,” says Kim.

She says the school runs the triathlon because it wants to see children getting fresh air and getting active.

'We just think it's a great event, getting kids outside, [and] you never know, you might have the next triathlete in our making.”

The triathlon is set to bring in plenty of five to 10-year-olds, Kim says, but convincing older children to participate is more of a challenge, and their dwindling participation is hard to peg on anything.

'We would love to see more 11 to 13-year-olds compete. It's hard to say [why they don't].

Puberty kicks in, some people think sports is not their thing, but we'd just like to see more of those kids come in.”

Children can register on the day, but limited spaces are available, with the event capped at 400 participants.