Thread:KockaAdmiralac/@comment-27875343-20161215172639/@comment-86484-20161215182649

As far as I could see, there was no fake sky in Snowdin, just trees and rocks, and areas where you can't see what's up because what's below takes up the whole screen. The whole Underground is a cave, with smaller tunnels and 'rooms' inside. One of these is the Wishing Room, where you can see the small bright rocks that Monsters use in place of stars, but I think the rest of Waterfall has only dark rocks above.

I wouldn't say Waterfall branches off from the rest of the Underground, it connects Snowdin and Hotland. The 'roof' seems to be lower in that area, and it has its own microclimate as all areas do, but it's a part of the Underground like all the others.