This is a rapid called Ruckachucky (sp) Falls and it's on the Middle Fork of the American River. Though this is not me in the photo, this is the largest rapid I have ever run. I've only done it once, on my last day as a professional river guide in the States.
Mark Ryan and I ran it together and it was damn amazing.
What you normally have to do, if you don't run it inside your boat, is let your customers off above, wade out to a pool just above the falls and shove your boat out into the middle of the river so that it goes into that slot. There is another slot just to the right of this (if you are looking down river. So in the photo it would be to the left). It is a keeper slot as the water pours through two rock and will trap your boat and ruin it.
However, this is a two man job, for you cannot just push your boat over a waterfall and expect it to be waiting nicely for you at the bottom. The job of the second man is to hike down below, climb up a rock about 20 feet above water level, and jump out about 15 feet to an eddy (a spot of calm water) about five feet by five feet that is right behind a rock. Mind you that this is all in the middle of rapids that are trying desperately to wash you down stream. You have the falls above you pushing all this water in your face and at your back you have a series of class IV rapids about ten meters down stream.
You then must scramble/slither up this rock (you can see it in the above and below shots, it's the one in the bottom right hand corner). Wait for the boat to be shoved down the falls, then, as it's rushing past you you must leap into the boat and paddle it into an eddy where the customers are waiting.