I had always assumed that whitewater kayaking was about getting down the rapids. In fact, it is more like skateboarding tricks: if you are good (or perfect, depending on the difficulty), you can do cool tricks, hang on waves, surf, actually go upstream, etc. Basically, seeing something that makes you say "Wouldn't it be cool if..." and then trying it over and over again until you actually pull it off. And the fun comes from the practicing, and trying it over and over again, where even if you completely mess it up, it is still a heck of a ride (and possibly a swim: the maneuverability and agility of the whitewater boats means they are very easy to flip).