Dreamsea
The Dreamsea is the name for the frontiers above the worlddisks of Charos where the colorless air above the disks meets the polychromatic dreammist of the space between. When used to refer to the totality of this area above all the worlddisks, or above all those of a particular orientation, the term is used more or less interchangeably in the singular and plural; one may refer to the Dreamseas or to the Dreamsea with the same meaning, and likewise with the Dreamsea[s] of Qabede or of Gaden. The term is exclusively singular, however, when used to referring to the sea over a particular worlddisk, such as the Dreamsea of Dadauar or the Dreamsea of Tammaz. Because of this, some sophists insist that the usage of the singular to refer collectively to the seas above multiple worlds is solecistic, and that in this sense the word is only properly used in the plural. Long-established usage, however, contravenes this prescriptivist claim. (Capitalization is also inconsistent; some sources capitalize the term Dreamsea, while others treat it as an uncapitalized common noun.)
Though it is, in one sense, nothing more than the boundaries between two different types or colors of gases or vapors, the Dreamsea is likened to a sea not without reason. Part of the reason is no doubt just the fact that the flat expanse of colored mist evokes an image of the similarly flat expanse of water in the sea. However, there's more to it than that; there are those who sail upon the Dreamsea in a way analogous to the way others sail upon the oceans. Enchantments exist that will make vessels "float" on the dreammists, upside-down relative to the worlddisks below (or above); many of these dreamships even closely resemble more conventional watergoing vessels—though by no means do all exhibit such pariformity, and some have shapes utterly unlike anything seen elsewhere.
Features
For the most part, the Dreamsea is an unbroken plane with dreammist below and air above. It isn't perfectly flat; the occasional billows and undulations occur, somewhat reminiscent of ocean waves but more irregular. Still, the bulk of the Dreamsea appears more or less featureless, just a colorful vastness stretching below an inverted world. The only things in the Dreamsea resembling solid land are the products of life. In some parts of the Dreamsea people have constructed artificial islands, fixing them in place with similar enchantments to those that make the dreamships possible. But natural "land" occurs as well, in the shape of the dreamreefs (just "reefs" to sailors there who don't have the need to distinguish them from reefs of the marine variety), built up by colonial organisms called costunacs and merryworms. These dreamreefs can often grow large enough to support substantial ecosystems, though rarely large enough to be visible from the surface of the nearby worlddisk.
The Dreamsea takes the first part of its name from the dreamdisks that occasionally appear within it—if not directly, then perhaps from the name of dreamspace or the dreammists which in turn take their name from the dreamdisks. In any case, dreamdisks seem to appear slightly more often at the surface of the Dreamsea than elsewhere in dreamspace, though they are still rare enough that sailors on the Dreamsea can go years without encountering one.
Near the edges of the worlddisks, the boundary between the air and the dreammist becomes less well defined, and the Dreamsea dissolves into a foggy homogene. Sailing into this area is risky at best, since as the sea dissipates so too does the dreamships' support, leading to the likelihood of a plummet through dreamspace.
Phenomena
Though the Dreamsea often seems placid and uneventful, in fact there are a number of unusual phenomena that occur there from time to time. Some of these phenomena have little consequence other than the cosmetic, such as the suffusions in which a large part of the sea takes on a common color, but others can pose a real hazard to sailors thereon. Risings, in which the colors of dreamspace rise to pervade the air above the sea, impede visibility. Rips, areas of turbulence in the Dreamsea, are a more direct peril that may include vorticial gurges that can draw unwary ships below the seas and into dreamspace where the enchantments fail that would keep them "afloat". Perhaps most dangerous are the dreamstorms, unpredictable bursts of strange and uncontrolled magics that can have devastating effects on unprepared sailors.
At the rims of the disks where the sea loses its stability, many strange phenomena occur—some transient, but some persisting indefinitely. Spontaneously arising rhegi have diverse effects, from agalmatation to disintegration. Among these effects, however, are natural portals called rimgates that may lead to the Dreamseas of other worlddisks, providing dreamsailors interested in travel to these disks a reason to venture to these dangerous fringelands—though preferably with a good map and a skilled navigator, to ensure that the ship makes it to the portal and doesn't blunder into some other enchantment or off the edge of the seas.
Life
The reef-building costunacs and merryworms are not the only living things to be found on the Dreamsea. In fact, while certainly sparse in comparison to that on most of the worlddisks themselves, life in the Dreamsea is much more common than in the depths of dreamspace. Something about the transition between dreammist and air generates some form of energy that certain microörganisms can draw on to support themselves, in turn providing nourishment for other entities higher on the food chain. Thus, though it may seem barren at first glance, there are a number of creatures that have adapted to this limital region.
Some of these are confined to the dreamseas of particular worlds, or of particular orientations, but others have managed to spread—or to appear independently and panasterically—all over Charos. Among these are the rainbow strider, the scudder, and the harpagon, as well as flora and quasiflora like skymoss, mum towers, and Bestra lilies. Mistlings form in the Dreamseas, though they seldom stay there long before descending to the worlddisk surfaces—unless they find suitable prey on the Dreamsea itself. There is even at least one breed of undead apparently unique to the Dreamsea, the dorburo, a twisted ghost of a soul slain in a dreamstorm.
In addition, some entities found throughout dreamspace occasionally "surface" at the Dreamseas, including murciars and bulrins. Even the enormous julistrabe is not a stranger to the Dreamsea, though it's a rare enough sight there to inspire sailors' tales. It's not entirely obvious why these creatures of dreamspace bother coming to the dreamseas; while infrequent, their visits to the dreamseas still occur a bit too often to be entirely due to random wandering. It could be that there is some substance or quality in the air of the worlddisks that they need but cannot acquire from the dreammists of space, though it could also be simply that they come there for the more plentiful food.
Dreamsailors notwithstanding, the Dreamsea has few permanent ellogous inhabitants. There are, however, a few former sailors who have decided to settle permanently on reefs or artificial islands, building structures there out of whatever resources are available, or out of imported materials. A few mages, too, have for whatever reason chosen to set up homes in the Dreamsea... or provide the means for wealthy recluses to do so.
Travel
Though in a way nothing more than a border between two different gases or vapors, the Dreamsea still can provide a sustinent medium for suitably enchanted vessels. These dreamships ply the seas, with many dreamsailors not setting foot on a worlddisk for years at a time. Because the Dreamseas are oriented upside-down relative to the disks below, sailors on the Dreamsea typically sail the seas of the disks of opposite orientation. Dreamsailors from Qabede sail the Dreamseas of Mriddiom, and vice versa; the same relationship holds for Gaden and Ckapir, and for Gaiua and Heqhesta. There are enchantments that can change the direction of a sailor's weight to match other worlddisks, however, and some choose to undergo such enchantments to be able to sail over their own homeworlds, or worlds like them—even if it means reversing the enchantment again if they ever want to return to the surfaces of those worlds. Furthermore, some of the rimgates connect Dreamseas of different orientations, and change accordingly the orientations of those passing through. It is, therefore, possible for sailors from worlds of any orientation to make their ways to Dreamseas of any orientation, though most dreamsailors prefer to preserve their original orientations if possible.
Reaching the Dreamseas in the first place is no easy feat. Generally the easiest method, in fact, is direct translocation to a known position there (or to a dreamship located by scrying or by other means of divination). Failing that, however, it is possible to leap off the edge of a worlddisk and land on a waiting dreamship or other surface on the dreamsea below—though (among other obvious difficulties) the fall is long enough that some means of slowing one's descent is highly advisable. The first dreamships, however, were probably set off in just this manner, by tipping them off the edges of the disks where they were constructed.