Just thought I'd formally request a waterfall tile for water flowing over ridges. I know that's a bit out there, purely aesthetic, and probably stupidly expensive to have rendered. But it would be nice to see sometime, eventually. For now I'm using my imagination where appropriate.
If it's done, I promise to render a version of something like the Missouri River's Great Falls (destroyed landmarks of incredible beauty and grandeur from North America's primitive past). River combat!
Falls should probably be completely impassible to boats, but simply costly to swimmers. Just as Ridges function to walkers and fliers.