Astral Sea

It is the space between everything. It is the road that goes everywhere. It is where you are when you aren't anywhere else.

— Wanderer of the planes

The Astral could be reached from almost any point in the Material plane or first layer of any Outer plane by spell, psionic ability, or device. It was described as a barren place of other-dimensional nothingness extending in all directions. What little solid substance that floated in the bright, gray void was typically chunks of matter broken off from their original plane. The Astral had no gravity but objects did retain their mass so you could throw small items or push off from large objects to move in the weightless environment.
Time in the Astral flowed at the same rate on a Prime Material plane but the effects of time were slowed almost to a stop―a thousand years in the Astral plane felt like only a day to the traveler. Creatures did not go hungry or age while in the Astral plane. For that reason, its mortal inhabitants needed to return to the Material Plane in order to have children or to reach adulthood.
Entering the Astral plane could be accomplished in one of two ways: projecting your astral form into the plane via the astral projection spell, or by physically entering the plane. Astral projection was the safest way to travel but still involved risk because you left your physical body behind on the traveler's plane of origin. The astral body would be accompanied by the astral forms of any items and clothing that were magical or radiated a magic aura. While projecting, your astral self was connected to your physical body by a silver cord that stretched out behind you for about 10 feet (3 meters), or 1 foot (30 centimeters) depending on the version of the spell, and then became invisible and intangible. Very few things could sever this silver cord: a powerful psychic wind, a githyanki silver sword, or the will of gods. The physical body left behind appeared alive but did not require food, water, or air and did not age. It could be moved and was vulnerable to damage and death. If the traveler's physical body was slain, death followed the projection some minutes later. If the astral self was slain, the traveler then returned to his or her physical body in a coma. Physically entering the Astral plane required 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 saw a silvery color pool nearby—a portal to the location on the Prime Material plane from which they originated. Astral projecting travelers saw their silver cord leading back to this pool. Color pools appeared as two-dimensional circles about 10‒60 ft (3‒18 m) in diameter and only visible from one side unless they had some way to detect invisible objects. Pools of different colors were portals to the different Outer planes. Each Outer plane had its own unique color, but the traveler's home portal was always a metallic silver, rippling like mercury in a pan. Color pools could be used to view the destination plane before stepping through by mentally concentrating on the nearby pool until it became transparent. A viewer could also move (with some limitations) the portal's viewpoint by concentration. Astral projecting travelers formed a new physical body (with silver cord attached) when they stepped through a color pool to their destination plane. The new body was formed out of local materials so the greater the similarity between one's home plane and the destination, the more one's new body looked like the original one.

Inhabitants

There are no real species native to this realm of thought, but the githyanki have long lived in their plane and have built large cities and fortressess here. All manner of creatures from any realm can be found here, be it fiend, celestial, or something else. Most notable were perhaps the feared Astral Dreadnoughts, who roamed the plane without goal, consuming anything in its path.

Languages

none

Color Pools

none

Ethereal Curtains

Swirling gray

Tuning Fork

Quartz, B

Shape and Size

Infinite

Gravity

none

Time

Flowing (1000 real years = 1 subjective day)

Type

Dimensional plane