The Astral Sea

Phlogiston is different than the The Astral Sea in 2nd Edition D&D, but in 5th Edition they are basically the same thing. in 5E It's the "Deep Space" between Crystal Spheres and it has special properties.

5e Articulation

The Astral Sea surrounds all the Wildspace systems, as well as the astral dominions of gods and the floating remains of dead gods.

Great Wheel

According to the Great Wheel cosmology model, the Astral plane connected the Prime Material Planes to the first layers of the Outer planes. In some versions of the Great Wheel cosmology held in the late 15th century DR, it was possible to travel to the Astral Sea directly from wildspace aboard a spelljammer. In this cosmology, wildspace was a region where the Prime and the Astral overlapped. Moreover, upon exiting a wildspace system such as Realmspace, a ship would leave this overlapping region and fully enter the Astral. The border between wildspace and the Astral Sea had the appearance of a silvery haze.

Once in the Astral Sea, spelljamming captains could steer their ships in the direction of other wildspace systems or specific locations in the Astral in the same way that individuals would traverse the plane: by concentrating their thoughts on the destination.

This view was in contrast with the prevailing Great Wheel cosmology of the 14th and earlier centuries DR, according to which a ship would encounter a crystal sphere at the edge of its system and, if capable of traversing it, would enter the phlogiston.

Alternative Name(s)

Astral Plane

Type

Plane of Existence

Included Locations

• Greyspace
• Krynnspace
• Realmspace

Official D&D Sources:

Astral Adeventurer's Guide