What Kim is referring to is called Infant-Swim Rescue (ISR) survival training. It's a very specialized form of swim training and instructors must be certified in it for it to be ISR. It is quite incredible and I have witnessed it myself firsthand - an 18 month old baby literally dropped in the deep end of the pool rolled over on her back with arms spread out and kick-swam herself to edge of the pool coping. She then grabbed the coping and held tight. No freaking out or crying or hysteria, just calm and simple swimming. It's incredible to see.
Here's what I did - I have the standard pool safety fence (self-latching/self-closing, proper height, width, etc, etc). I also happen to have a home alarm system and I set it to beep every time a door/window/entry is open (pretty standard feature). All of the doors that lead out to my yard have what are called "pool code" dead-bolts. In addition to normal handle and dead-bolt lock set at the usual height, there is a second deadbolt set 30" from the top of the door frame. It is high enough so that only a child of ~ 8 years of age could reach it. Sure, my mischievous 4 year old could try to move a chair over to it, but he'd be caught well before ever reaching the door.
Other than that, it's swim lessons for the kids every year until they reach about 6 years old or so and I'm confident they can swim and tread water.
