Just a pool, disguised as a pond, with a trampoline instead of a diving board. These pools have a natural filtration system that run based on the plants that are in the pool that give the water nutrients that allow it to not only be crystal clear, but you are also able to drink the water because it becomes so clean.
Some farmers around here have bought a steel granary, and each used one level to make a pool, curving out some of the bottom, getting a pool liner, and using weeping tile around the top, so the edges are not sharp. Works great, and bigger than a trough. I LOVE this idea!
natural backyard swimming pool, no chemicals. @Sherry S @ Young House Love. Sherry, I figured this might catch your attention since it has no chemicals. Not sure about the reality of such a pool, but, it's an interesting idea!