"Most of our kids don't get many chances to learn how to swim, but once they sign up to the TRYathlon, parents start encouraging them to go to the pool, and practise swimming instead of just doing bombs - it has a really far-reaching effect," McFarlane said.
"It doesn't just boost the kids' morale, it changes the way parents encourage the children too."
Sport Bay of Plenty spokeswoman Melissa Gordon said being involved with the TRYathlon was the perfect fit with the organisation's goal to get more school-aged children active more often, particularly with the event being about participation rather than winning.
"This is a fantastic opportunity to give children from low decile schools in Rotorua the chance to participate," she said.
"These children get a sense of achievement, excitement and huge confidence boost from being involved in such a great event. This is a real chance for them to discover there are events out there for everyone to take part in, no matter what their ability level."
Trust chairman Stewart Edward said the decision to fund discounted entries to low decile schools stemmed from the trust's recognition of the importance of encouraging young people into exercise and outdoor activities.
"Our involvement really underpins the opportunity for young people who wouldn't typically be able to afford to have these same experiences as their peers," he said.
"By funding these discounted entries we are able to inspire children to take part in new activities that interest them."
Sanitarium spokesman Nigel Chenery said the company was delighted to see Sport Bay of Plenty give Rotorua school children the chance to take part in the TRYathlon.
"It's fantastic to see thousands of children every year training for and completing this event, no matter where they live, what their fitness level or sporting ability.
"Last year we had more than 1000 entrants in Rotorua; it would be fantastic to see that number grow even more this year.
"The event is about encouraging Kiwi kids to get active and healthy while training for a specific goal. We know receiving a medal at the end of the event gives all the participants a feeling of pride and accomplishment, and that's what the series is all about."
The TRYathlon series is open to children aged between 7 and 15, and consists of a swim, followed by a cycle and a run.
Participants wanting to register for the December 2, 2018-2019 event can visit try.weetbix.co.nz