Though the researchers of the study insist that the results are rock solid, I am skeptical. The study was conducted by Australian and New Zealand researchers whose cultures are obsessed with both swimming and the sea. Both nations, who sport small populations have produced not only the best swimmers and surfers per capita on the planet but they have produced the best sailors the world has ever known. Thus I believe that the study should have included other activities like dancing, arts and crafts, t-ball, etc. etc.
From Science Daily:
Hence, it's my belief that stimulating a toddler with any sort of exercise plan that involves organization and reward will exact the same result.
Researchers from the Griffith Institute for Educational Research surveyed parents of 7,000 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 says 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.