I learned to swim as a teenager via a class at the Y. The regular parks and rec dept swim lessons when I was 5 or 6 just didn't "take" for some reason. Anyway, in the Y class, at the end of the first class meeting, they literally pushed you off the low diving board into the deep end. An instructor was down below with a bunch of kick boards floating around to grab onto. I think that's what got my fear going, more than anything else. Plus, I remember seeing a 20/20 story 25+ years ago about pool drains that had too much suction and would rip out the insides of kids who sat on them (there's wasn't an auto shut down on the system like has to exist now). Stupid thing, but it freaked me out. Still kind of does. Pools don't have these kinds of drains anymore, regulations don't allow them, but dang, why that has stayed with me all this time, I have no clue. Lakes (I've never been on the ocean, just stuck my toes in the Atlantic last year) don't have drains.