Hmmm... the wider river looks more plausible, but something is still off.

I think it's the islands... not sure if its the overall shape or what, but they feel disconnected to me?

In the *thumbnail*, and zoomed out, the river banks (and the definition of the hills) look smudged. Close up, they look really good Looks like your land continues, under the water.

Your islands don't have that look, but really, they *are* hills under the water... So I'm wondering if A) You can give them the same effect, and B) If the smudginess in the thumb bothers you at all.

Everything else looks really great, as far as I can tell.