The competition on Saturday will be held at the Tikioki Tri site, starting at 2pm.
Cook Islands Triathlon Association president Roland Neururer said there would be three different age categories.
Neururer said the competition would include a swim, bike and run, with both individuals and teams of three invited to participate.
The 9 and under will do a 100 metres swim (or walk in the water), 3 kilometre cycle and 1km run.
“Entry is free and there are some great prizes and giveaways to be handed out.”
Neururer said the main aim of the event was to let children have a go at triathlon and have fun in the sun.
“Everyone is asked to be at the tri site by 1pm. See you there.”
Meanwhile Lettuce Smoke You won the annual Corporate Team Triathlon Challenge which was held earlier this month.
The team representing Oasis Hydroponics finished the swim, bike and run in 1 hour 17:34 minutes.
Carter Cruises finished second with a time of 1:19:38 hours followed by RHR of Tereora College in third place with a time of 1:20:10 hours.
Thirty teams took part in the challenge which included 200m swim, 8km cycle and 2km run.
The season opening corporate challenge is designed to be a fun event to get people into triathlon.