1.8 Updates: First Ravines, Now Rivers
In this recent tweet, we can see the first released image of a game-generated river! It's a safe bet at the moment that it will face similar height restrictions as default water generation, but that may change in time - after all, we already have legitimately generated waterfalls!
We will keep you posted as more information about rivers is released.
@Tampashrew
Q:"Is that one of the big red mushrooms at the bottom?"
A: No, it's a new type of tree =)