Whanganui mother-of-two Elizabeth McMenamin-Pervan said she had to hire Carlton School's pool and her own instructor once a week to get lessons for her oldest son, who has special needs.
"It just shows that there's nothing out there for my kid, so I've had to organise it myself," she said.
Her youngest son is enrolled at the Splash Centre.
"It's a necessity that everyone learns to swim, and it's a necessity that kids learn the basics before they get to primary school."
Whanganui District Council took over operations of the Splash Centre from Sport Whanganui at the start of September.
As of September 27, 631 out of 750 slots were taken for swimming classes in Term 4 at the Splash Centre, aquatic services manager Erica Rowe said.
All children must undergo an assessment before joining a programme to determine which class they join.
If students wanted to move up a level in lessons, parents had to go to the Splash Centre on a particular morning to re-enrol, Whanganui mother Tori McDonald said.
"If you're not in a privileged situation you have to get your kids up and out of the house and line up at 7am.
"When the child is staying at the same level you just sign up again there and then. I don't see why they can't just do that in general."
Rowe said the Splash Centre's "rebook day" for swimming lessons this year was held on a Saturday instead of a Monday, because of the public holiday for Queen's Memorial Day.
"This resulted in longer queues than usual.
"Whanganui District Council is investigating solutions to streamline the booking process in future."
Another mother stood in the rain and signed up for her child this year, McDonald said.
"That was really kind of her.
"She managed to get the last two places, for her daughter and my son."
Lifesaving programmes didn't teach people to "swim from nothing" and there needed to be more programmes in Whanganui that facilitated that, Newell said.
"Two or three funded people would really kick things off.
"There could be masses of kids doing swimming, beach safety and education, and water awareness."
Whanganui resident Mark Kennedy said he had no luck securing swim classes for his 11-year-old grandson.
"You try and get into the Splash Centre and they are generally booked out a term ahead. It's very frustrating."
He said he was now looking into lessons at The Marton Swim Centre.
"When my kids were growing up they all learned to swim by the time they were 6.
"Now, you just can't get into anything. There is only one swim school."
McMenamin-Pervan said having to go to the Splash Centre in the early morning to enrol was "archaic".
"You can't do it online, you can't call them, and you can't email them.
"There are mums who have to put all their kids in the car, drive them there and try and sign up.
"That's ridiculous."
Fellow mother Flis Cassar Torreggiani said her 5-year-old had been "in and out" of lessons because of a trip overseas.
"I finally went to see family for two months, so now I have to go through the rigmarole of trying to get her back in again."
Cassar Torreggiani said she had been trying to get her youngest child into lessons for two and a half years.
There was now a chance of enrolment through the Splash Centre's school holiday programme.
Whanganui was a growing city and that had to be accommodated, she said.
"Swimming is considered an important life skill in this day and age, and you [Splash Centre] are the only major swim school.
"I'm not entirely sure what isn't working. I don't know if it's a lack of staffing or if whoever runs it doesn't want to increase the number of lessons."