Dreamspace
"Dreamspace" is the name given to the empty expanse between worlddisks on the plane of Charés, just as "outer space" refers to the empty expanse between stars and other celestial objects in Tamamna. (And, like outer space, it's often called just "space" for short when this wouldn't result in ambiguity.) The worlddisks are far apart, and dreamspace is unfathomably large--just how large is impossible to say, since it's not known whether or not Charés is finite.
Calling dreamspace "empty" is, in fact, accurate only in relative terms. Certainly there's little solid matter aside from the worlddisks, and while there are some living organisms native to dreamspace they're certainly far sparser than on the disks. But all of dreamspace is permeated with the varicolored spacemists, thin and transparent but still thicker and harder to see through than air. Then, too, there are the dreamscapes that give dreamspace its name, short-lived scenes that flicker haphazardly into existence in random locations, and then flicker back out again just as abruptly.
Travel
{main|Travel through dreamspace} It is possible to move through dreamspace, to travel from one world to another. Certainly few creatures could do it of their own volition--even those with the power of flight would tire long before they reached a destination so unimaginably far away. But spacefaring ships have been constructed capable of making the journey, in all sorts of sizes, from small spaceskiffs that only hold a handful of people to great spacegoing galleys the size of a large city. Those who actually embark upon such voyages are few, and on most worlds traveling through space is a thing unheard of--but, on the other hand, there are some few advanced worlds where it's been so long practiced that it's now considered fairly routine.