The Ethereal Plane
The Ethereal Plane is a transitive plane that exists alongside the Prime Material Plane, its Echo Planes, and the Inner Planes.
It is a mist-filled expanse dominated by shades of gray, white, and black. Fine particles drift through the surrounding fog, and visibility remains limited even where no physical obstruction is present.
The plane is divided into two broad regions: the Border Ethereal, which overlaps neighboring planes, and the Deep Ethereal, which connects these border regions to one another.
Unlike the Astral Plane, which provides the principal route toward the Outer Planes, the Ethereal is primarily associated with the Prime Material Plane, the Feywild, the Shadowfell, and the four Elemental Planes.
Structure and Environment
The Ethereal Plane has no conventional ground throughout most of its expanse.
Mist and pale fog extend in every direction. Travelers retain a general sense of orientation and can distinguish above from below, but there is no natural gravity drawing creatures toward a surface.
The plane contains a breathable atmosphere. Food and drinkable water do not normally occur there, however, so travelers remaining for extended periods must bring their own supplies.
Visibility is limited by the surrounding mist.
Conditions differ considerably between the Border Ethereal and Deep Ethereal. The Border retains a recognizable relationship with the plane it overlaps, while the Deep Ethereal contains few ordinary landmarks.
The Border Ethereal
The Border Ethereal is the portion of the plane that directly overlaps another plane.
A traveler within it occupies an ethereal counterpart to the same general location on the adjacent plane. The surrounding landscape remains visible but appears muted and indistinct, with colors fading toward gray and edges blurred by the Ethereal fog.
Buildings, terrain, creatures, and other objects on the adjacent plane can normally be observed but cannot be touched.
Travelers in the Border Ethereal can pass through most physical objects belonging to the overlapping plane. Walls, doors, water, and ordinary terrain therefore provide little obstruction. A lake on the Material Plane can be crossed without swimming or drowning, while a mountain can be passed through without excavation.
The relationship largely works in one direction. Creatures within the Border Ethereal can perceive the overlapping plane, while inhabitants of that plane normally cannot see or hear ethereal creatures without magic or another ability that allows them to do so.
Certain magical effects can reach across the boundary between an overlapping plane and its Border Ethereal. Force-based magic is particularly effective at doing so, and specialized wards can be created to detect, obstruct, or affect ethereal creatures.
The Deep Ethereal
Beyond the Border Ethereal lies the Deep Ethereal.
Here, the recognizable features of neighboring planes disappear. Travelers are surrounded by shifting mist, colored fog, and drifting concentrations of ethereal matter, with few fixed points of reference.
Large masses of protomatter move through the Deep Ethereal. These substances have no permanent form and can gather, separate, or change as they drift.
When a sufficiently large concentration of protomatter stabilizes, it can begin forming a demiplane. These demiplanes vary greatly in size and environment. Some remain small or temporary, while others persist long enough to develop stable terrain, structures, or inhabitants.
The conditions that determine whether a mass of protomatter becomes permanent are not fully understood.
Movement and Travel
Movement through the Ethereal Plane is directed largely through intent.
A traveler chooses a direction and moves through the surrounding mist without requiring conventional ground. There is enough orientation to move upward or downward, but neither direction carries the normal effects of gravity.
Movement within the Border Ethereal corresponds broadly with movement across the neighboring plane. This makes it possible to enter the Border Ethereal on one side of a physical obstacle, move through its ethereal counterpart, and return on the other side.
Travel through the Deep Ethereal is more difficult. Without recognizable geography, travelers rely on ethereal curtains, magical navigation, established routes, or guides familiar with the plane.
Moving blindly through the Deep Ethereal can leave a traveler far from any useful passage back to another plane.
Connections to Other Planes
The Ethereal Plane provides the principal transitive route between the Prime Material Plane, its Echo Planes, and the Inner Planes.
The Border Ethereal overlaps the Prime Material Plane, the Feywild, the Shadowfell, and each of the four Elemental Planes. Every location within one of these planes therefore has a corresponding region within its Border Ethereal.
The Deep Ethereal connects these separate border regions. A traveler seeking another plane can enter the Deep Ethereal, locate the appropriate ethereal curtain, and pass through it into the Border Ethereal associated with the destination.
This allows travel between the Prime Material Plane and the Elemental Planes of Air, Earth, Fire, and Water, as well as the Feywild and Shadowfell.
The Positive and Negative Energy Planes do not possess ordinary Border Ethereal regions and are not reached through the network of ethereal curtains. Travel to them requires direct planar magic, established portals, or other controlled crossings.
The Outer Planes likewise do not share the same relationship with the Ethereal. Travel toward them is normally conducted through the Astral Plane instead.
This distinction makes the Astral and Ethereal complementary parts of planar travel rather than interchangeable routes.
Ethereal Curtains
Ethereal curtains are planar boundaries found throughout the Deep Ethereal.
They appear as broad surfaces of vaporous color suspended within the surrounding mist. Passing through one carries a traveler from the Deep Ethereal into the Border Ethereal associated with another plane.
Different destinations produce different colors and appearances, allowing experienced planar travelers to identify some curtains before crossing them. Knowledge of these signs is particularly valuable because entering the wrong curtain can leave a traveler within the Border Ethereal of an entirely different plane.
Some curtains remain stable enough to become established routes. Others shift, disappear, or become difficult to locate as the surrounding Deep Ethereal changes.
Time
Time passes normally throughout the Ethereal Plane.
Travel through the Border or Deep Ethereal does not inherently alter the passage of time relative to the planes they connect. Individual demiplanes within the Deep Ethereal may possess unusual temporal properties, but these are features of those demiplanes rather than the Ethereal Plane itself.
Interaction with Overlapping Planes
The Border Ethereal provides an unusual position from which to observe the plane it overlaps.
Objects and terrain appear indistinct and drained of color, as though viewed through heavy mist or frosted glass. Details become harder to distinguish at greater distances.
Sound is similarly limited. Nearby voices or loud noises may sometimes be perceived, but they become increasingly difficult to distinguish with distance.
The Ethereal Plane provides enough diffuse illumination for travelers to perceive their immediate surroundings. A creature observing a dark location on an overlapping plane does not necessarily require its own light source.
Someone on the adjacent plane normally has no indication that an ethereal observer is nearby. This makes ethereal travel useful for reconnaissance and infiltration, though magical defenses capable of detecting or affecting ethereal creatures can counter these advantages.
Inhabitants
The Ethereal Plane has inhabitants of its own in addition to planar travelers.
Ghosts are frequently encountered within the Border Ethereal, particularly around places to which they remain attached.
Phase spiders also make extensive use of the plane. They move between neighboring planes and the Ethereal while hunting, allowing them to approach prey from directions that ordinary physical barriers would prevent.
Other creatures have adapted specifically to the Ethereal Plane, including ethereal marauders and ethereal filchers. Some spend most of their existence within the Ethereal, while others move between it and neighboring planes to hunt, travel, or avoid danger.
The Deep Ethereal is less thoroughly documented. Creatures encountered there may travel between curtains, inhabit drifting fragments of matter, or remain near developing demiplanes.
Protomatter and Demiplanes
Protomatter is one of the most distinctive substances found within the Deep Ethereal.
It appears as drifting masses within the mist and lacks the stable structure of ordinary matter. Small concentrations may disperse without consequence, while larger masses can persist and gather additional material.
When enough protomatter accumulates and stabilizes, it may begin developing into an independent pocket of planar space known as a demiplane.
Some demiplanes are deliberately created through powerful magic, while others appear to form naturally within the Deep Ethereal.
Their environments do not need to resemble the Ethereal Plane itself. A demiplane may contain conventional gravity, air, terrain, structures, or other conditions depending on how it formed.
Many are isolated and can only be reached through a particular portal, ethereal route, or magical effect. Because the Deep Ethereal is difficult to survey, the total number of demiplanes within it is unknown.
Natural Hazards
The Ethereal Plane is not inherently hostile to mortal life, but travel still carries significant risks.
Becoming lost in the Deep Ethereal is among the most serious. The surrounding mist provides few landmarks, and ethereal curtains can be separated by considerable distances.
Travelers may also encounter hostile creatures, ghosts, or other beings capable of interacting with them despite their ethereal state.
Returning from the Border Ethereal requires care. A traveler attempting to return to an overlapping plane while occupying the same location as a solid object may be displaced to the nearest available space.
Ethereal curtains create another risk. An unfamiliar curtain may lead to an Elemental Plane whose environment requires immediate protection.
Developing demiplanes and unstable concentrations of protomatter can also produce unpredictable conditions within the Deep Ethereal.
Survival
The Ethereal Plane is relatively hospitable compared with many of the planes it connects.
The atmosphere is breathable, temperatures are generally survivable, and travelers in the Border Ethereal can bypass many physical hazards present on the overlapping plane.
Food and water must normally be brought from elsewhere.
The principal difficulties are navigation, hostile inhabitants, and finding safe routes between the Border and Deep Ethereal.
Travelers remaining close to an overlapping plane can usually return through the same means that brought them into the Border Ethereal. Journeys through the Deep Ethereal require greater preparation, particularly knowledge of ethereal curtains, reliable navigation, and the conditions of the destination plane.
For planar travelers, the Ethereal Plane provides one of the principal routes through the physical and elemental reaches of a Reality Sphere, just as the Astral Plane provides access toward its Outer Planes.