Ethereal curtain

Ethereal curtains, also called curtains of vaporous color, were the barriers between the Deep Ethereal and the various Border Ethereal regions of the Ethereal Plane. Some scholars instead reported a single infinite curtain that separated the two regions of the Ethereal, in which case it was called the Wall of Color.

Description
Ethereal curtains appeared like enormous sheets of colored vapor, which continuously were in motion. The motion had been described as the flapping of a world-sized flag. Motes of sparkling light flickered over their surfaces. Some who had seen ethereal curtains described them as looking something like the northern lights found on some worlds.

The curtain or curtains were only visible from the Deep Ethereal side and never from the Border Ethereal.

Anyone separated by a curtain from the Border Ethereal was completely protected from any harm by any force or being on the other side, whether on the Border Ethereal or the bordered plane.

Curtain Colors
The color of an ethereal curtain indicated to which Border Ethereal region it led. To those who believed in a single ethereal curtain, the curtain had separate colors in different areas, which indicated the destination. Trusting in the color of the curtain to lead you to your desired target, however, was considered risky. The colors of the curtains to most of the major planes are listed in the table below, along with other methods of planar travel:

Travel
If a traveler faced an ethereal curtain, desire alone was all that was necessary to enter through the curtain and find oneself on the other side, at the border of another plane able to see into it from the Ethereal. (Strangely, something prevented anyone from reaching the Border Ethereal of the Material Plane around Krynnspace; the ethereal curtain to this part of the multiverse was somehow blocked. ) Likewise, any planar traveler desiring to leave the Border Ethereal of any plane needed only to will it, and she or he would immediately appear facing an ethereal curtain of the appropriate color. To an observer still remaining on the Border Ethereal, the traveler would appear to vanish in an enveloping, roiling mist. (An exception to this was found on the Border Ethereal of the Demiplane of Dread, from which it was impossible to enter the Deep Ethereal. ) Later scholars believed that the only way to enter the Deep Ethereal from the Border Ethereal was with a plane shift or gate spell.

Traveling along a curtain before entering it would allow one to appear at a point overlapping a different location on the bordered plane, but since it was not possible to see through the curtain, it was generally not possible to predict which direction of travel along the curtain would lead to which location, nor did distances traveled in the Deep Ethereal in any way correspond to distances in the Border Ethereal. Some travelers of the planes argued that those who were clever enough could recognize patterns in the flashing lights in the curtain to find previous sites of entry.

Traveling to another curtain or area of a curtain could feel like a journey of anywhere from 10 to 1,000 hours,  though the time that had actually passed in the Material Plane would not be as long. Traveling to the place where passage through a curtain would take one exactly to the desired destination in the Border Ethereal always took longer than if someone simply had willed to reach a given border in general.

If a visitor to the Deep Ethereal was under the effects of a magic item or spell, such as etherealness, and the duration of the magic wore off, the traveler would immediately be forced through the nearest ethereal curtain and would materialize on the corresponding plane of existence.

Appearances

 * Tantras
 * The Fallen Fortress
 * Ghostwalker
 * The Howling Delve