Out With the Old
The Astral Sea is, except as noted here, more or less as drscribed on p. 46 of the Dungeon Master’s Guide.
The inner/lower planes are more or less isolated from the Astral Sea, and few to no Astral portals lead to the inner planes. The Outer Planes are also altered from the standard. Rather than a neat ring of planes representative of all the alignments, they are scattered islands floating in the Astral Sea, occasionally home to deities of rather varied alignment. Often, these will resemble planes as described in the Dungeon Master’s Guide, but without as strong an allegiance to a particular alignment.
Each plane is an “Island” in the Astral Sea, which is largely similar to the Astral Plane. Portals to the planes, color pools, are scattered everywhere, but vast, ocean-sized “pools” mark what most consider to be the plane’s “location” in the Astral Plane, and the frequency of pools connecting to a particular plane increases as one approaches the “main” pool. Often these pools are connected by long “strands” of color in a vast web through the Silver Void, so that by happening upon a strand of the right color and following it, one can eventually find a portal to one’s intended plane. Pools and strands sometimes offer glimpses of the planes to which the lead as well.
Astral Color Pools and Strands
Typically a color pool’s destination plane can be guessed based on its color. A color pool is usually roughly circular, and 1d6x10 feet in diameter. However, larger , irregular color pools the size of lakes have been encountered, and the astral real estate of each outer plane is marked by one the size of a vast sea.
d20 Plane: Color and Description
1-2 Arvandor: Emerald Green, with glimpses of trees and rushing water
3 Carceri: Deep rust red, and no hints
4-5 Celestia: Gold, with the occasional glimpse of mountains
6-7 Chernoggar: Flickering red and orange, with glimpses of military formations
8 Hestavar: Sapphire or sky blue with glimpses of high towers
9 Archanus: Transparent and filmy, slightly refractory and iridescent
10 Kalandurren: Pale gray, with no glimpses
11-12 Nine Hells: Ruby red, no glimpses of what lies beyond
13 Pandemonium: Magenta, sometimes one can faintly hear the wind
14 Pluton: Iron gray
15 Shom: Pale silver-blue, sometimes with paler patterns that suggest sigils
16 Tytherion: Indigo, sometimes with dappling that suggests scales
17 Unstable: Color flickers and varies wildly
18 Ethereal Plane: Spiraling white and pale gray, suggestion of fog
19 Material Plane: Silver
20 Other Planes: Multicolored strand, usually leading to a demiplane or other planar realm
Note that Astral color pools do not normally connect to the Inner Planes nor to the Parallel Planes. In order to reach those planes, one must connect through the Ethereal Plane.
Another important navigational feature of the Astral Sea is the Meridian, an apparently flat midpoint of rippling light, as if the light of an unseen sun reflecting off invisible waters. The Meridian is a ribbon of faint light that connects to all of the Color Seas of the outer planes, but only appears flat on observation in reference to itself; a traveler leaving the Meridian at a perpendicular angle (as if rising vertically from it) may find herself intersecting with it again from another angle if she keeps her heading long enough.