A pool for sure, I had a nasty experience with trying to swim in the ocean when I was about 9 so I haven't tried since that.
(seriously...pretty much every square inch of water had a freaking JELLYFISH in it! Do not want. x_x )
I like lakes too but sometimes worry about what's in them that I can't see.
Pool, I love the smell of chlorine. But I don't mind lakes and ponds. I'll go in the ocean but not very far out and I usually will use a boogie board because ever since I got stung by a dying jellyfish that was washing up on shore, I have been terrified of getting out too far and being completely in the water .
POOL. I don't like lakes, ponds, or the ocean. I want to see what is swimming next to me aside from the stuff that is microscopic. I told like sea weed feel on my body, I don't like sand in my crack, and I don't like the fishy smell. I won't swim in anything, but a pool. I lived right on the lake growing up. (Lake Erie) And I use to swim all the time, but it's not for me anymore. Now that I know the luxury of pools, I'll never go back.
Pool! I like playing in the sand at the ocean, but I'm not much for swimming there. Plus, I'm not that great a swimmer anyway. I honestly prefer to sit in the kiddie section of the pool. It's shallow, usually goes past my waist when sitting, and there's no one there trying to jump on top of me. (I just hate when people pay no attention to those around them at the pool, and throw a ball at your face or jump on you or something. Grr). That's a rant for another thread though.