Astral Sea
The Astral Plane is the realm of thought and dream, where visitors travel as disembodied souls to reach the Outer Planes. It is a great silvery sea, the same above and below, with swirling wisps of white and gray streaking among motes of light like distant stars. Most of the Astral Sea is a vast, empty expanse, with wildspace systems scattered hundreds-of-trillions of miles apart. Visitors occasionally stumble upon the petrified corpse of a dead god or other chunks of rock drifting forever in the silvery void. Much more commonplace are color pools — magical pools of colored light that flicker like radiant, spinning coins — or storms of dangerous, displacing psychic wind.
Creatures on the Astral Plane don’t age, breathe, or suffer from hunger or thirst. For this reason, humanoids that live on the Astral Plane (such as the githyanki) establish outposts on other planes, often the Material Plane, so their children can grow to maturity.
The volatility and mutable nature of the Astral Plane makes most forms of teleportation and magical travel between two "places" in the Astral Sea difficult. However, a free floating traveler in the Astral Plane can move by simply thinking about moving, though distance has little meaning and being "here" in the Astral Sea is only different than being "there" because you think it is. One need only to think of a destination and intuit the path to find it; even an abstract idea of a destination, such as "the nearest available restroom" or "second nearest githyanki outpost", is enough to divine the direction. In combat, for the sake of mechanics, a creature’s floating speed (in feet) is equal to 3 × its Intelligence score. The smarter a creature is, the easier it can control its movement by act of will.
Planar travelers and refugees from other planes wander the expanses of the Astral Plane. The most prominent denizens of the Astral Plane are the githyanki, an outcast race of reavers that sail sleek astral ships, slaughter astral travelers, and raid planes touched by the Astral. Their city, Tu’narath, floats through the Astral Plane on a chunk of rock that is actually the body of a dead god.
Celestials, fiends, and mortal explorers often scour the Astral Plane for color pools leading to desired destinations. Characters who linger for too long in the Astral might have an encounter with one or more wandering angels, demons, devils, night hags, yugoloths, or other planar travelers.
A creature or ship that wants to travel from one wildspace system to another must cross the Astral Sea unless it has some other magical means of traveling from one world in the multiverse to another.
Wildspace systems aren’t fixed in certain locations in the multiverse. Because they’re constantly in motion, like corks bobbing in water, no reliable devices exist to help plot a course from one wildspace system to another. Fortunately for travelers, the nature of the Astral Sea makes such journeys relatively easy, as discussed in the next section.
The Astral Sea does not have gravity or air. However, in the Astral Sea a creature can survive indefinitely, never aging or breathing and never feeling hunger or thirst.