It's pretty nice to swim at that bottom most waterfall there too ^^
If you want so swim above the waterfalls or in the middleparts, then I'd ask the locals for advice on where it is safe to do so.
[MENTION=834]Dragon[/MENTION] already mentioned it, Tepui, but I was marveling at it again today - specifically Mount Roraima. It's definitely at the top of the list of places I'd love, love, love to visit.
This is a decent article discussing the area - it just sounds amazing: