Thanks, guys. It takes days to get it right to be honest. Here's a version with (1.5x) stretched foam. Part of it anyway, as the little 'breakers' foam is assigned to the breakers themselves and they are stretched in the width of the stream. The foam around the rocks is assigned to the distribution of the rocks, and shifted half a meter downstream.
The guy is huge, which is off. The stream is 6m wide, by the way. The canoe is 3.5 meters, maybe a bit small. But this is about the water anyway. I've added more rocks on the riversides, but I think to make them smaller, or several sizes. Or some huge ones, I don't know. This one took 2.5 hours @detail 0.5 and AA 4. It needs higher settings, but not at this stage.