Yea, it drove me bonkers, but it is doable. I have even went back and did it a third and fourth time, but I have to think about it each time I do it.
To get the raft to cross the river, click the red ball on the opposite side. But a raft operator has to be on it.
You have to think outside of the box... it takes a bit, but this is by far one of the most challenging puzzles that I have ever done!