i believe it's around the age of 2 or so that children start to gain that fear of drowning (despite they do not understand death necessarily)
my little cousin (now two) 'had' swimming lessons as a younger baby (6months-1year) where they teach the bady that once they are IN the water how to roll themselves onto their back so they can breathe of course, my cousin's house is near a lake and so to be extra careful her parents did that
it was really cool and her mom said it was hard watching them throw her in the pool
Babies do it automatically I heard a scientist say that it is because they "swam" in the womb and that it's second nature to them to be in water. I don't know when they go from instantly holder their breath to panicing and needing swimming lessons
i remember one time on the swim team swimming in a competition pool, where instead of them using chlorine, they used salt! took my goggles off and stuck my head in the water, does not sting, its pretty cool. kind of made the pool floor slippery and the water taste funny when it got in your mouth...