Astral Plane
From Ardrana
To some it's the most dreadful of nothings, an unrelieved expanse of silver, worse than the fog of the Ethereal Plane. For others the Silver Void (as it's also called) is a place of subtle wonder, with patterns in the shades that hint at greater things. The Astral Plane looks empty, but there's a lot drifting in it.
The most common things a basher's going to see there are the color pools - gateways to the Outer Planes. These hang in the void, shimmering in prismatic colors like the surface of a pond.
A few primes have let out the chant that the pools are color-coded, letting a body know which plane they lead to, but as usual they're wrong. One smart thing to know, though, is that a sod can use a color pool like a window, to see where he's going, if he looks through the colorful side and concentrates on what's beyond. It's sad the number of leatherheads who don't know that trick.
Color pools are one-sided, and a being can hit one from its backside without seeing it. Passing through a color pool - from either side - spits a traveler out onto the uppermost level of that pool's plane. Moving through a color pool's been described as kind of like pushing through warm molasses - the pool kind of surrounds a body when he presses against it.
Astral conduits to the Outer Planes are another feature of this plane. These look like whirling funnels, except they've got no ends. No matter how far a sod travels, these conduits seem to go further. Conduits are dangerous, too, because they tend to thrash around and can suck up a traveler and spit him out someplace he don't want to be.
More dangerous than the conduits are the githyanki, who'd just as soon put a sod in the dead-book as talk to him. Their homes are built on great islands of matter sucked out of other planes by the creation of a new conduit. Larger githyanki settlements are sometimes made on the drifting corpses of long-forgotten powers.
Weakened beyond awareness, these powers have been cast out of the planes to drift helplessly in the silver void. Not dead yet not alive, these so-called "god-isles" are slowly crumbling in an undying decay. Occasionally a dim glimmer of awareness stirs the power, and sometimes its thoughts and dreams overwhelm the squatters upon it. There's also the githyanki ships - bizarre vessels powered by thought alone, used to hunt the astral whales and dreadnoughts of this universe.
Numerous little things are also found on the Astral Plane, like arrows soaring in endless flight, enemies banished to the drift in the void, and even dangerous magic that's been cast out here for the safety of all.
Note: The Astral Plane appears in more detail in the Guide to the Astral Plane from TSR. Its use here is for the purposes of providing context for the campaign only.