It may look insane, but the guy at the picture is not a Photoshoped silhouette placed over a fake landscape. He's swimming at the Devil’s Pool, a natural rock pool at the very top of the Victoria Falls, at Zimbabwe, with a height of about 100 metres.
From Wikitravel: You will have the opportunity to stand in shallow water, 2 inches (literally) from where the water gushes over the edge of the falls, and swim in Devil's Pool, a reasonable current-free pool a couple of feet from the top of the falls, close enough to lean over the edge. This makes fantastic photo opportunities with a permanent rainbow from the mist of the falls behind you".
Source Link - http://fogonazos.blogspot.com/2008/02/swimming-at-edge-of-victoria-falls.html