Geographically, the Void is very mountainious, with rocky spires reaching heights of several miles. The vegitation is very jungle-like, with fauna similar to a rainforest.
Humans tend to stay in the spire-like mountains, away from the ground and thick forests. While on the other end of the spectrum, Watchers tend to stay in the forests, jungles and desert regions of the Void.
It appears there was at one point a ancient civilization in the Void, evidenced by crumbling stone structures, buildings, and ancient ruins. It is unknown which race, Humans or Watchers created it, or if it was a race unique to the Void itself.