Drowning Doesn't Look Like Drowning
A drowning person doesn't wave their arms; they're using them to keep their head out of the water.
A drowning person doesn't yell; they haven't got enough breath.
Drowning looks nothing like what you've seen on television.
Roughly half of all children who drown do it within 25 metres of a parent or other adult, and in 10% of the cases, the adult watches it happen because they don't recognize what they're seeing.
Please read the linked article to learn what drowning really looks like, and please heed its advice--if your kids are in the water and they go quiet, get to them quickly and find out why. Someone who is drowning can only keep themselves at the surface for 20 - 60 seconds.
Article by Mario Vittone, found via Janet Reid's Twitter.