Also included for the adults is a kayak option which replaces the swim leg.
Sport Northland events manager Azelia Parkinson said it is great to have the different options available because almost anyone can take part.
"The cycle course includes some significant hills and with the run course being largely off road this adds further mental and physical demands on athletes," she said.
"Bearing this in mind it is great to see so many taking up the challenge and entering this event."
The long-course event - a 700m swim or 1.5km kayak, 20km cycle and 8.5km run - often proves to be a challenge.
The short-course event - a 350m swim, 10km cycle and 3.8km run - will attract many beginner triathletes and those wishing to have a go, while the kids' section offers varying distances.
The girls and boys 7-year grade will take on a 50m swim, 4km bike and 1km run. The swim increases to 100m for both the 8-to-10 age grade and the 11-to-15 one.
The day will conclude with a prizegiving. The Kai Iwi Lakes event is preceded by the Northland Secondary School Sports Association (NSSSA) Team & Individual Triathlon, which runs on February 23.
Students from Whangarei Boys High and Girls High students will have a target on their back after the schools made a clean sweep of the major placings in the senior and intermediate events last year.
Kurt Coetzee and Portia Olney-Kemp took out the under-19 individual divisions, while Lucas Thompson and Alysha Donavan won the under-16 individual events.
In the 2017 junior event, Huanui College students Luka Clark and Grace Gardner won their divisions.
The prizegiving includes a range of spot prizes to participants, including Thermatech gear, Samsung Galaxy Tablet from NorthCloud and Fullers GreatSights cruises.