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While on the Ethereal Plane, a creature is called ethereal.
Ethereal creatures are invisible, inaudible, insubstantial, and scentless to creatures on the Material Plane (the normal world). Even most magical attacks have no effect on them. See invisibility and true seeing reveal ethereal creatures.
An ethereal creature can see and hear into the Material Plane in a 60-foot radius, though material objects still block sight and sound. (An ethereal creature can’t see through a material wall, for instance.) Things on the Material Plane, however, look gray, indistinct, and ghostly. An ethereal creature can’t affect the Material Plane, not even magically. An ethereal creature, however, interacts with other ethereal creatures and objects the way material creatures interact with material creatures and objects.
Ethereal creatures move in any direction (including up or down) at will. They do not need to walk on the ground, and material objects don’t block them (though they can’t see while their eyes are within solid material).
Force effects are a special exception. A force effect extends onto the Ethereal Plane. Gaze effects and abjurations also extend from the Material Plane to the Ethereal Plane. None of these effects extend from the Ethereal Plane to the Material Plane.
Ghosts have a power called manifestation that allows them to appear on the Material Plane as incorporeal creatures. Still, they are on the Ethereal Plane, and another ethereal creature can interact normally with a manifesting ghost.
Ethereal creatures pass through and operate in water as easily as air.
Ethereal creatures do not fall or suffer falling damage.