The boulder clog is most often full of wood, so scout it and see what you think. There are a variety of possible routes, but none of them are easy and neither is the portage. A standard line if there is no wood is to go to the left side of the rock-pile island and take the far left slot and immediate the far left slot, though stay right in this slot to be up on a boulder to boof off. The run out is class IV down to the eddies above Flight Simulator.