Color pool

Color pools were gateways that led from the Astral Plane to other planes of existence. These "pools" were scattered about the Astral Plane     and unique to it, and they were the most common feature of that endless expanse. The plane to which a pool led could sometimes be determined by the pool's color. Most scholars believed that there were an infinite number of color pools to any given plane adjacent to the Astral, yet at the same time, some planes seemed easier to reach by color pools than others.

Location
While color pools were plentiful and likely the most common feature to be seen by a visitor to the astral, this was relative to the vast size of the Astral Plane. It would usually take a visitor to the Astral anywhere from 6 to 24 hours of astral travel to reach the nearest color pool from any given point.

Even so, one didn't have to know of the precise location of any color pool; if you were to visit the Astral Plane, you only had to think about going to a pool leading to your desired destination and you would eventually find such a pool. If you had been to that planar destination before, you would find an appropriate pool even more quickly, thought not a particular pool to a particular place on that plane.

Githyanki pirates often cruised from color pool to color pool in their astral skiffs, searching for victims.

Description
Color pools seemed to viewers like irregular-shaped, shimmering disks of opaque color in the otherwise monochrome space of the Astral Plane. They were two-dimensional, being infinitely thin on the edge and about 10 to 60 feet (3 to 18 meters) in diameter. Some sages supposed them to be composed of a mixture of "liquid reality" mixed with "astral energies".

Color pools were only visible from one side, which could be problematic, as they were functional from any direction; one could easily pass through the invisible side, without even being aware of doing do, and appear instantly in another plane of existence.

Pool Colors
A strange feature of the magic of color pools was that the pool through which one entered into the Astral always appeared silvery in color to the traveler. Such silver pools seems very much like rippling liquid mercury. If travelers had entered by means of an astral projection, their silver cords led back into this silver pool.

It was said that all other pools had a color that indicated their destination, but some scholars of the planes warned that this idea of a "color-code" for the pools was dangerous nonsense.

Those planar scholars who believed in the existence of alternate Material Planes said that the pools to such planes were always of other metallic colors than silver, such as bronze or brass.

All other planes supposedly had non-metallic colors for their pools. For example, a color pool leading to the Ethereal plane was like a whirlpool of watery milk. For the pools leading to any other plane, the colors described by the sages were remarkably consistent, and are provided in the table shown here.

Travel
Every Outer Plane could be reached from the Astral through a color pool, and the pool led most often to the first layer of any plane.

When a traveler entered through a color pool in an astral form, the silver cord extended into the new plane, and a physical form was instantly created for the traveler appropriate to the new plane. The silver cord remained connected, all the way back through the color pool, through the Astral, and through the silver-colored pool back to the traveler's original body, which remained in stasis. It was impossible to enter the Astral with astral projection and return to the original plane through any other color pool except the one through which the Astral had been entered. Such other color pools back to the original plane would simply cease to function.

If a spellcaster using astral projection took a group along, everyone else in the group was instantly pulled through the color pool once the spellcaster had passed through; they had no choice in the matter, and the magic of the spell forced them along.

A traveler who had managed to enter the Astral plane in physical form had no such limitation. For her or him, passing through any color pool physically and instantly transported both body and mind to the new plane, even if it was another location on the plane of origin. In any case, to an observer on the destination plane, a travel would simply appear out of nowhere.

Where exactly a color pool led on the destination plane varied greatly; it could be in the sky, underwater, underground, or on the surface. Unlike portals, the destinations of color pools were not intelligently planned; they were random.

Moving through a color pool felt like forcing oneself through a thin, soft membrane, or through warm molasses, which resisted and surrounded the traveler until giving way, at which point, the traveler burst through to the other plane. It was not possible to insert only a portion of one's body through a pool; the entire body had to pass through at once, as soon as enough force was applied to break through the "membrane".

Only about fifteen to thirty percent of color pools allowed returning from the destination plane; the rest were essentially a means of "one-way" travel. A "two-way" pool was not invisible at the other end but appeared as a gaping hole in reality into the Astral Plane. Most such two-way pools were guarded closely by the inhabitants of the destination plane. These portals could even be moved to other locations. Many were used for interplanar trade, and a few trading towns had been founded around them. Two-way color pools were one cause for the presence of non-astral creatures found in the Astral Plane on occasion and for many other large astral objects.

An even smaller number of color pools were both two-way and immovable. Such cases were called "fixed portals".

Scrying
It was possible to see through a color pool like a window to its destination if the viewer concentrated intently on the pool  from within a close range of about ten yards (nine meters). If the viewers were using an astral projection, only the caster of that spell could see through the pool to the other side. If a group of planar travelers had entered the Astral Plane physically by other means, then the most intelligent individual could control the result of the viewing.

When observed with such mental concentration, the pool ceased being opaque and became fully transparent, providing a view from between 100 and 400 yards (90 and 370 meters) above the surface of the target plane. If the viewer were mentally capable enough, he or she could to attempt focus the image toward a particular place on that plane, but the location viewed might still be anywhere on that plane despite this. Using a color pool like a scrying pool in this way was termed "using an astral window". Viewing the destination plane in this way in no way changed the actual location one might arrive if the color pool were entered.

Once a location had become visible, the scrier on the Astral plan could actually move the image around at a rate dependent on her or his intelligence, at a maximum rate of about six miles per hour (nine kilometers per hour). Strangely, moving the image around was much slower in areas with high magical activity, such as cities with a large population of wizards. Moving one's vantage point in such a way did not permit passing through solid objects or through any space smaller than the diameter of the color pool itself.

It was possible to use this technique to scry into large buildings, if their ceilings were high enough. Placing a thin strip of lead within the structure of a ceiling could defend against such unwanted observation from the Astral Plane. It was not possible to cast a spell through an "astral window" from the Astral side.

Some creatures or powerful spellcasters could sense when they were being scried on in this way and fog up or seal off the color pool or even attack the scrier on the other end. Color pools could only be sealed off slowly, however, shrinking in size until vanishing, and it was usually possible for the scrier and any companions to pass through the pool to the destination, if they desired to do so before it fully closed.

To detect such a scrying attempt through a color pool usually required a spell or magic item such as see invisibility or true seeing. Creatures that could harm a scrier by attacking back through the color pool when viewed included monsters with gaze attacks, such as basilisks, cockatrices, or medusas.

Once someone had used a pool to scry on its specific destination, the destination would not change for a length of time equal to a day on the Material Plane.

Using a pool as an astral window wore out the viewer, and the average human could only carry out such observation for under two hours. The window would remain focused where the viewer left it for up to ten hours before reverting, and it could not be used to scry again for at least 20 hours after that.

Observing through a color pool to the Ethereal came with an additional risk of being accidentally sucked into the ether cyclone on the other side. All color pools from the Astral to the Ethereal led into the heart of an ether cyclone; it was impossible to scry anywhere else on the Ethereal plane.

History
Some planar scholars postulated that color pools were the result of damage caused to the fabric of existence of the Astral Plane caused by all of the magical travel through it. Unlike planar conduits, which seemed to age and may have been created by some higher powers for a purpose, color pools seemed ageless and random in their placement. More pessimistic folk suggested that the increasing interplanar travel was leading to more frequent psychic storms as a result of the weakening caused by the pools.