"Many of these skills are those that help young children into the transition into formal learning contexts such as pre-school or school."
Jessica Bell, 4, has been taking swimming lessons with Manurewa Swimstation since the start of the year.
Her father, Chris, said he'd noticed his daughter's confidence grow immensely since starting the 20-minute classes.
Especially compared to the confidence Mr Bell's eldest daughter, Almina, had at Jessica's age - Almina didn't learn to swim properly until she was 7 because the family lived in the Philippines until then.
"It's just really important to know how to swim, especially in this country, and you don't really get that from going to the beach. It's a skill they should get to have as soon as possible and a lot of schools don't really do a great job. In fact a lot of schools don't even have pools anymore," Mr Bell said.
Fleur Scott got her two children, Hayden, 4, and Caitlin, 6, into the water at 6-months-old so they would be familiar with the water.
Mrs Scott, of Manurewa, said she wasn't that surprised by the research because the swimming lessons had given her children "massive confidence boosts", especially around water.
"And it teaches them to be independent, they have to swim off away from adults on their own, and they also learn to be more social with the playtime after class," she said.
Manurewa Swimstation instructor Danielle Strom said it was instantly obvious which children had been to swimming lessons earlier. Ms Strom said it was vital children learned to swim, especially in New Zealand because we're surrounded by water. It also improved other aspects of their lives.
The study, released yesterday, was a joint project between Griffith University, Kids Alive Swim Programme and Swim Australia.