Eco-tourism at its best! There is a certain time of year (September - December) when the water level of the Victoria Falls is low enough that people can swim to the edge without fear of falling over. This is because there is a rock wall just below the water that protects them from being carried over by the current.
I doubt I'd have the balls to do this...would you? Oh did I mention Victoria Falls is the largest waterfall in THE WHOLE WORLD!!! No wonder its called the "Devil's Swimming Pool".