The Astral Plane
The Astral Plane, also known as the Astral Sea, is the space between the planes, a great, endless sphere of clear silvery sky, both above and below. Large tube-shaped clouds slowly coil into the distance, some appearing like thunderheads and others looking like immobile tornadoes of gray wind. Erratic whirlpools of color flicker in midair like spinning coins. Occasional bits of solid matter can be found here, but most of the Astral Plane is an endless, open domain. The Astral Plane has no gravity but objects do retain their mass so one could throw small items or push off from large objects to move in the weightless environment.
The Eternal Archive, the realm of Io and Ao, the twin dragon deities representing Time and Space, is also situated within the Astral Plane.
Time in the Astral flows at the same rate on a Prime Material plane but the effects of time are slowed almost to a stop―a thousand years in the Astral plane feel like only a day to the traveler. Hence, it is sometimes considered effectively timeless. Creatures do not go hungry or age while in the Astral plane. For that reason, its mortal inhabitants need to return to the Material Plane in order to have children or to reach adulthood.
The Astral plane connects the Prime Material Plans to the first layers of all the Outer planes. Wormholes link specific places in the Outer planes to each other and to fixed locations in the Prime—quicker but likely more dangerous because one's physical body is transported directly to a terminus that might be inhospitable or guarded.
When a character moves through an interplanar portal or projects their spirit to a different plane of existence, they travel through the Astral Plane. Travel in the Astral is usually accomplished by spell, device, or color pool and involves leaving one's physical body behind while their astral self travels to their destination. Even spells that allow instantaneous movement across a plane, such as dimension door, briefly touch the Astral Plane.
During this transit, a nearly unbreakable silver cord connects one's astral self back to their physical body. Very few things can sever this silver cord: a powerful psychic wind, a silver sword, or the will of gods. The physical body left behind appears alive but did not require food, water, or air and did not age. It can be moved and was vulnerable to damage and death. If the traveler's physical body is slain, death follows the projection some minutes later. If the astral self is slain, the traveler then returns to his or her physical body in a coma. Physically entering the Astral plane requires a spell such as plane shift and brought travelers wholly into the Astral with no silver cord to anchor them to their plane of origin.
Upon entering the Astral plane, travelers see a silvery color pool nearby—a portal to the location on the Prime Material plane from which they originated. Astral projecting travelers see their silver cord leading back to this pool. Color pools appear as two-dimensional circles about and only visible from one side unless they have some way to detect invisible objects.
Pools of different colors are portals to the different Outer planes. Each Outer plane has its own unique color, but the traveler's home portal is always a metallic silver, rippling like mercury in a pan. Color pools can be used to view the destination plane before stepping through by mentally concentrating on the nearby pool until it becomes transparent.
A viewer can also move the portal's viewpoint by concentration. Astral projecting travelers form a new physical body (with silver cord attached) when they step through a color pool to their destination plane.The new body is formed out of local materials so the greater the similarity between one's home plane and the destination, the more one's new body looks like the original one.
Both planar travelers and refugees from other planes call the Astral Plane home. Astral searchers, astral streakers, astral whales, the mighty astral dragons, and the tiny kodragons inhabit the Silver Void. The dreaded astral dreadnoughts are believed by some to be a manifestation of the Astral Plane itself, while others point to their indefinitely long tails as an indicator for an origin elsewhere. Brain collectors, dhours, and foo creatures can all be found here.
All manner of fiends, celestials, slaadi and other planars use the Astral as shortcuts to their business elsewhere, but both astral devas and shedu patrol the plane regularly to keep evil in check. Despite their connection to the Abyss, bebiliths were thought to be at home on the Astral plane.