Jackson swims amazingly, we don't have a fence around the actual pool, just a fenced in yard that the pool is in. I don't worry about Jackson much because he won't swim unless I am out there anyway, he does lay on the step occasionally w/o me. But he has been swimming for 5 years now and knows how to get in/out of pool. He's only fallen in twice and that was when he was being a dummy and gets over-excited at four wheelers etc driving by our fence and doesn't pay attention where he's running, and both of those times he nonchalantly just kept swimming towards the steps. So he doesn't panic.
Lilly, on the other hand, our JRT mix has fallen in a few times the same way (over excitement, running and being hyper) and she flips out and acts like she doesn't know where she is, even though we put her in the pool a lot to practice and get her to the steps. So we watch her closely. We didn't start her as young in the pool though and I wish we would've.
Actually in this video, she almost does a 'slip' when she was running towards Jackson as he was diving in:
https://www.youtube.com/watch?v=YMV2...nJy0e5dC5PD9qA
I would just teach them how to swim - for one, it's FUN! and they get good exercise, encourage them to enjoy it, use treats or favorite toys... and swimming is an essential life skill. Even if you can't get them to like it, they need to at least KNOW.