My route was east to... is that frog? I can't remember, whichever that was. I figured out which island grub was with the map and the clues about the winds that use grub as a marker, so I knew where I had to get to and I knew the red stream was roughly in that direction if I could get close enough to drop into it (those were the two main pins placed on the map). Randomly I just tried the others until I went that vague direction - hopped into the highest stream and that got me most of the way, dropped into the lowest when I knew I'd be in that zone and it got me to the island proper.
So it was my third island, sort of by fluke of just trying streams and seeing where they felt good.
I feel like wind sounds and sail rotating sounds would mean you could navigate almost by sound and feel alone, that might be cool too.