A nitpick, sure, but it leapt out at me. By the blue boat the water is moving far too fast for a dead end. It should be far more calm.

A slightly more detailed/long winded The water flows from the waterfall to a T junction-if it goes right (assuming you follow from the waterfall) it goes offscreen. If it goes left, it enters what is either a deadend or a very well hidden/clogged-by-rock underground entrance that wouldn't support water flowing that quickly; the area would flood rather quickly.