I didn't know about the raft either, but for the collectibles, if
you take your children and drop them in the small circle between
the black plant and the waterfall, the collectibles will show up quicker for a short time. I've gotten them all, but one butterfly, and now that I know about the raft, I'll be looking forward to it.
I've solved all the puzzles and have a bunch of totems, so come on butterfly!