The Astral Plane, also known as the Astral Sea or the Silver Void, is an almost entirely empty expanse of drifting, hazy clouds of milky white, ashen blackness, and shimmering specks that would resemble stars if not for the fact that they come in a range of colors and tend to appear and vanish at random every few days. More information than what you see here can be found in the Dungeon Master's Guide (pages 46-48) and the Astral Adventurer's Guide (pages 20-22).
While in the Astral Plane, creatures feel neither hunger nor thirst. They continue to tire, however, so sleep and rest remain necessary.
The effects of any poisons or diseases affecting a creature are paused while the creature is in the Astral Plane. The effects resume as soon as the creature leaves the plane.
Creatures in the Astral Plane do not age. Time, however, continues to pass at the same rate as it does in most other planes. One hour in the Astral Plane is the same as in the Material Plane.
Creatures must breathe while in the Astral Plane, but fortunately the entire plane is filled with breathable air, or something like it. Even aquatic creatures are able to breathe while in the plane. Sound travels as it would through air, and fire burns just as readily.
Occasional winds sweep through the plane. Rarely, however, these “psychic winds” escalate into gales that can blow travelers off-course and leave their minds in tatters (see the Dungeon Master's Guide, pages 47-48).
The plane is full of drifting clouds and streaks of silvery light, which in most parts of the plane provides a dim light comparable to the illumination of the full moon at night. The distance one can see varies greatly. At times the plane can be quite empty, allowing creatures to see for miles in any direction. At others, it can be lightly or heavily obscured, as if by fog.
Although the Astral Plane is largely empty, it is not entirely so. Debris floats like driftwood through the silver sea. Githyanki pirates ply the void aboard astral ships. Ageless monsters, such as the astral dreadnought, skulk through the plane's depths and hunt unfortunate travelers. And more than one long-forgotten god is interred here, their corpses (or “god isles”) picked apart by the eons, bereft of worshippers to sustain them.
The Astral Plane is a realm of pure thought. While there, a creature can move in whatever direction it pleases simply by thinking about it. The creature's speed (in feet) is equal to its Intelligence score times 5.
However, most vessels and certain other unique objects (like the god isles) exert a kind of gravitational force. While in the presence of these objects, creatures move in their normal manner and at their normal rate.
The Astral Sea is a “transitive plane” that joins many other planes of existence. The specks of light that can be seen throughout the plane are portals known as “color pools," 10-60 feet in diameter. These portals can lead to the Material Plane, the Ethereal Plane, the Outlands, or any of the 16 Outer Planes. Color pools to the Material Plane always appear within Crystal Spheres, never within the Flow.
Color pools appear at random and linger for anywhere from a few hours to several weeks before vanishing. If a traveler has a particular plane they're trying to get to, they can find a pool that will lead to some point in that plane after about 10-40 hours of wandering, but there is no guarantee it will take them remotely close to their final destination within that plane.
A color pool's color reveals the plane that it leads to. They are visible only from one side, appearing invisible from the other. By concentrating on a color pool while nearby (or by using an aethervane or other divination magic from afar), the surface of the color pool can be changed to become like a transparent window that shows the precise location on the other side.
| d20 | Plane | Pool Color |
|---|---|---|
| 1 | Ysgard | Indigo |
| 2 | Limbo | Jet black |
| 3 | Pandemonium | Magenta |
| 4 | Abyss | Amethyst |
| 5 | Carceri | Olive |
| 6 | Hades | Rust |
| 7 | Gehenna | Russet |
| 8 | Nine Hells | Ruby |
| 9 | Acheron | Flame red |
| 10 | Mechanus | Diamond blue |
| 11 | Arcadia | Saffron |
| 12 | Mount Celestia | Gold |
| 13 | Bytopia | Amber |
| 14 | Elysium | Orange |
| 15 | Beastlands | Emerald green |
| 16 | Arborea | Sapphire blue |
| 17 | Outlands | Leather brown |
| 18 | Ethereal Plane | Spiraling white |
| 19-20 | Material Plane | Silver |
A creature can visit the Astral Plane via the 9th level spell astral projection, but this does not allow the creature to fully enter the plane. Instead, the creature manifests in the plane as a psychic projection of itself, which remains connected to the creature's physical body by a trailing silvery cord extending from between the creature's shoulder blades and fading out of view after about 1 foot. The spell allows a creature to travel through the Astral Plane for 1 hour, and when it ends, the creature returns to its physical body. If the creature manages to pass through a color pool or some other form of portal before the spell ends, the creature's body is transported to the new destination.
Spelljammers can traverse the Astral Plane just as they do the Material Plane, and this is the preferred mode of transport for most astral visitors. Traveling by spelljammer is far faster than flying by the power of thought alone, plus the ships can carry large groups of people and supplies all at the same time.