I don’t know much about materials etc, but would it be possible to do a slowly scrolling riverbank, from the point of view of a boat on the river, as a material? Or would it have to be some kind of procedural landscape? What I’m after is just a piece of scenery- the player would never get that close to it.
You basically want to look at the water example that comes in the learning tab.
Then use a panner to make it softly pan along the length of a mesh or spline.