Pool. Lakes are gross. And you can see beneath the surface in a pool, if we're talking about what I think we're talking about.
Woods (tree canopy) or meadow (open sky)?
Total fantasy of mine, but I don't think I'd ever really do it. I love the thought of sex outdoors and write about it, but that's in Lush Land and I don't think I'd ever really do it to be on display.