As well as achieving physical milestones faster, children who swim also scored significantly better in visual-motor skills such as cutting paper, colouring in and drawing lines and shapes, and many mathematically-related tasks.
Their oral expression was also better as well as in the general areas of literacy and numeracy, found researchers from the Griffith Institute for Educational Research in Australia.
The study surveyed parents of 7000 under-fives from Australia, New Zealand and the US over three years.
A further 180 children aged 3, 4 and 5 years have been involved in intensive testing, making it the world's most comprehensive study into early-years swimming.
Lead researcher Professor Robyn Jorgensen said the study shows young children who participate in early-years swimming achieve a wide range of skills earlier than the normal population.
"Many of these skills are those that help young children into the transition into formal learning contexts such as pre-school or school," Jorgensen said.
"The research also found significant differences between the swimming cohort and non-swimmers regardless of socio-economic background," Jorgensen said in a statement.
