Friends of ours have this amazing man-made pond/pool in their backyard. It has a liner and a pump, but pretty much everything else is natural. The sides mesh right up with the grass and it has a natural organic compound that keeps the algae out and pond dye that makes the water a dark blue green color. In all other respects, it's just like a regular pond. No maintenance for the winter either...just let it freeze and then play broom ball :)
I have never seen anything like it. It's amazing!
Speaking of amazing...who ever thought my 4 and 6 year old would have the guts to climb this tower and jump off an 18ft high dive! And for the faint at heart there is a giant rock which jumps well too.Untitled from JoshandJodi on Vimeo.