The Astral Sea, or the ethereal realm, is a plane that most Mortal Races will only experience as an out of body experience, or by a glimpse of matters behind the veil of their physical reality. The Astral Sea is a nebulous plane which holds all other planes within it. Due to the Astral Sea’s amorphous nature attempts to map or mark locations within it is not only futile, but fundamentally misunderstands it’s nature. The Astral Sea commonly appears as an endless plane of ephemeral mist that occasionally forms intangible features that resemble the other plane that is metaphysically closest to it.
The only plane of existence held by scholars to not exist within the Astral Sea is Death itself.