The Realms, now they’re home, and ye know enough to recognize trouble when it raises blade or hand to smite ye. Ye will have no such comfort in space. Some places even the gods avoid!
– Elminster of Shadowdale
A first-time traveler to the Astral Plane would find almost nothing familiar. A person by himself would float freely, and move in any direction with a thought. Age, hunger, and thirst have no meaning while floating in this infinite space. The stuff of the Astral Plane is to some extent amenable to the willpower of those traversing it. A being can fix a firm idea in mind of a destination and head in the direction that seems right. Eventually, the traveler will get there, though the route might not be swift, safe, or optimal. This intuitive form of navigation is what most creatures use when projecting to the astral, or when they find themselves on the Astral Plane in a physical body. It is, at best, unpredictable and, at worst, hazardous to even the most skilled traveler.
The Astral Sea is a realm defined as much by one’s perception as it is anything else. Here, perception can directly influence reality. Most humanoids think of the silver astral realm as a great sea, and astral skiffs, spelljammers, githyanki pirate ships, and other vessels treat the plane as if it were a great ocean. They’re greatly aided in this belief by the constant astral winds that make actual sailing more reliable here than it is on the world’s oceans. Since perception shapes reality, the astral winds form reliable tides, channels, and currents that a skilled helmsman can navigate if they know the means. With the proper charts and tools, a navigator can not only reliably find his way to a world he’s never been before, he can often estimate the amount of time it will take… something that’s impossible with intuitive navigation alone.
The Astral Plane is omnipresent and potentially has links to every other plane in existence. Many individuals pass through the Astral Plane without realizing it when they cast certain spells, like dimension door. They only find themselves on the Astral Plane only when something goes wrong, such as when a bag of holding is stuffed inside a portable hole. When something has to go somewhere else but has no other direction to go, it usually ends up on the Astral Plane.
There are permanent portals between various planes of existence and the Astral. A number of openings known as color pools float on the Astral Sea like flotsam on the ocean. Color pools are irregular disks of color floating in the vastness of the Astral Plane, and each connects to other planes, though some may not allow a return trip.
Astral Hazards
Just as the astral sea has currents, it also has storms, pirates, and hidden hazards beneath its waves.
Storms, Whirlpools, and Other Anomalies
Boiling with the unresolved magic of creation, the unpredictable Astral Sea can create arcane storms to harry the unwary traveler. Storms move fast, though less commonly, they can dissipate on the spot, leaving a ship eerily becalm. Other astral hazards are stationary and permanent. The most common of these is the whirlpool, a swirling vortex of energy that draws objects inexorably to its center to be battered by the force of astral space as it folds in on itself.
Astral navigators refer to other permanent astral hazards as anomalies. Movement patterns might follow a predictable course through the Flow, or drift arbitrarily, buffeted by astral currents. Many anomalies indirectly owe their existence to the activities of the gods, whether recently or deep in the mythic past.
Psychic Storms
There are winds in the Astral Plane, but aside from those that make up the flow, they rarely blow more strongly than a light breeze. Occasionally, part of the astral flares up into a psychic storm. These storms usually brew up with little warning, and those caught within the grip of a psychic wind might be blown off course and suffer mentally from the psychic turbulence of the storm.
Astral Objects
Bits of solid matter are strewn through the Astral Plane. Most of these objects have been sucked through color pools or left behind by careless (or deceased) adventurers. Such treasure may be in the form of a locked chest, a dead body, or a bag of holding that met an ugly fate when it was put inside a portable hole and cast onto the Astral Plane. Valuable treasures found in this manner often have powerful owners who want their valuables back.
Dead Deities
What happens when a deity dies? The Astral Plane is where the physical forms of those deities rest—the deities’ graveyard. The massive forms of long-forgotten deities float in the depths of the astral sea. These vaguely humanoid lumps are anywhere from a few hundred feet to several miles long. Some races, including the githyanki, have used dead deities as bases of operation.
Astral Encounters
Creatures found on the Astral Plane, with a few notable exceptions, tend to be from the various planes that the Astral Plane touches. While many are spelljammers themselves, some creatures have the natural ability to plane shift into this realm, some cast spells that allow them to do so, and some find their way to the Astral Plane through portals and magical mishaps.