Astral Sea
The Astral Sea, also known as the Astral Plane, is a Dimension beyond the Material Plane.
Description
Geography
The Astral Plane is one of the boundary dimensions that lie between many of the other dimensions. It is an amorphous realm where the will and the imagination have influence over the surrounding space, where one can will oneself to float and move. Some creatures whose species have been there for a long time have learned to actually shape the amorphous matter and energy into structures and objects. They, therefore, tend to be very psychic-oriented.
Time in the Astral Sea flowed at the same rate on the 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 reach adulthood.
Entering the Astral Sea 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 Sea 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.
Geographical Features
Upon entering the Astral Sea, travelers saw a silvery color pool nearby—a portal to the location on the 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 were only visible from one side unless they had some way to detect invisible objects. Pools of different colors were portals to the different Dimensions. Each Dimension 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.