I will only swim in man made pools/ the ocean that is clear enough that I can see through. I have nightmares about falling into lakes/rivers with all those big fish, lake plants, murky water. I hate it and it freaks me out and gives me anxiety. The last time I was in the ocean I had to doggy paddle around without touching the bottom because I was so freaked out.
While looking for a fishin spot we ran across clear water (no kidding). We could see everything fish, tree stumps, even lures that were snagged off poles. That was an amazing place for a swim and fish.
I've swam in all of the above.. but, living in Texas right now.. there isn't really a good place for me to swim. No access to a pool, the lakes in this area are nearly completely dried up and any water I can get into wouldn't be the smartest thing to do.