Absalom does not use the standard Inner and Outer Planes model adopted by many fantasy games. Instead of multiple planes, there are a limited number of dimensions, some closer and easier to get to than others. All of the dimensions, unless otherwise stated, share similar physical characteristics; they have oxygen, gravity, time passes at a similar rate, etc.
Mortal Realm. The dimension in which Absalom exists.
Shadowlands. A dim reflection of the Mortal Realm, the Shadowlands are where the souls of the dead voyage upon death, where they will make the ultimate voyage to the metaphysical center of the Shadowlands – the Plains of Rebirth, where they will be re-incarnated in the Mortal Realm. More information on the relationship of the Shadowlands to the undead in PHM #2 – The Entrance to the Valley of Kings.
The Shadowland geography maps almost exactly to that of the Mortal World, except for the following:
► Water does not exist in the Shadowlands, but then, neither does the need to drink or eat.
► Terrain features and man-made objects present in the Mortal Realm also exist in the Shadowlands; terrain features seem somewhat worn and eroded, while man-made features are only reflected in the Shadowlands after they’ve existed for a long time in the Mortal Realms, or been the scene of great trauma, death, or magical expenditure.
► Passage from the Mortal Realm to the Shadowlands can be accomplished virtually anywhere, either via death or magic.
The Shadowlands and Mortal Realm can be thought of as two sides of the same coin.
Faery. A dimension similar to the Mortal Realm, inhabited by the various races of Faery. In Absalom, these are the traditional fey races such as pixies, sprites, dryads, treants, etc. as well as goblins, kobolds, elves, dwarves, and others.
Faery is divided into multiple Courts – the two main Courts being Summer and Winter – ruled over by various Faery Lords with almost complete control over their domains. Faery has no geographic connections to the Mortal Realm; two portals within a few miles of each other in either dimension can lead to destinations hundreds, or even thousands, of miles apart.
Travel between the two realms is accomplished primarily through the use of portals that lead to fixed locations. Faery has no direct connection to the Shadowlands, and the residents of Faery do not have souls that are reborn, as those of mortal creatures are. Fey creatures, therefore, cannot be reincarnated or otherwise brought back to life after death.
Mortals visiting Faery comment on its vividness. Everything in this realm is just a little more intense; the colors more vibrant, the smells more potent, the air clearer.
Dreamlands. The Dreamlands are a dimension that most mortals can access, as the name implies, via a form of lucid dreaming. Here, the geography of the world is vastly different from the Mortal World, and the fundamental laws of physics and magic may not apply.
In the Dreamlands, one may travel to one of the many moons on flying ships, or palaver with intelligent talking cats, or gambol with ghouls in graveyards the size of a kingdom. Many of the gods worshipped in Absalom either dwell here or have their essence tethered here.
When dreaming, the voyager tends to arrive in the same place within the Dreamlands each time they enter, regardless of their physical location. Gates to Absalom do exist – the most famous being the Plateau of Leng, located in Areas 25 and 30 on the Overview Map. Here, the essence of dreams spills into the Mortal World, creating the display of lights known to Man as the aurora borealis.
The Dreamlands can be accessed via all dimensions, although it is not clear if each dimension has their own Dreamland, or if they are all accessing the same version. Likewise, it is not certain if the Dreamlands contains the Elemental Matrix, or if it is the other way around.
The Elemental Matrix. At one time it was thought that the worlds were created with elemental matter, each drawn from a distinct plane, but it is now known that the worlds are formed from matter and energy drawn from a single source: the Elemental Matrix, a vast dimension of pure matter.
The four main elements – Air, Earth, Fire, and Water – dominate the Matrix and are roughly divided into, if not regions, then vast concentrations of pure elemental matter. Where two or more elements touch strange, and obscure elemental material is formed – steam, and mud, and, ice, and others.
The main inhabitants of the Elemental Matrix are, of course, elementals, although the inhabitants are as varied as those of any other dimension.
Traveling to the Elemental Matrix is accomplished via magic, either specific spells that allow such travel – in which case the caster can usually specify their destination – or gates which lead to fixed locations. These gates are usually located in areas with high concentrations of elemental material; a gate to a zone of water may be located in the depths of the ocean, for instance.
As far as can be determined, all of the dimensions noted above can access the Elemental Matrix.