Sounds like its pretty tedious work, but I'm sure you enjoy it. My suite-mate has a drawing pad and he's told me about the uses of it since he's into art and he works on the school's weekly magazine.
In any event, its not so much that the river is a would be an after-thought, but the fact that theres the "wall", especially on the left side and the way it's arranged. The lack of depth in the river and the rocks make it seem like a cave/barrier (similar to what Kelley said) and the more I look at the most recent picture, I am drawn more and more to the "cave". As I've said, moving the rocks diagonally invites the viewer to everything in the tank. As for the risks/experiments, no risk no gain right?
