Lockheed and the Land of Waterfalls

I have to admit that I didn't choose this ad for the airplane or the destination. Sure the Lockheed Lodestar was a great little airplane and that South African Airways has a storied history, but it's the falls I'm interested in talking about.the nature of waterfalls.

Notice the one featured in the ad, the one that pours into...nothing. I'm interested in the land of disappearing waterfalls. Maybe it drops thousands of feet into an underground realm peopled by trolls, orcs, and goblins? Maybe it showers down on the lost city of Shangri La? All I can say is that doesn't happen in nature.