The Astral Plane

The Astral plane was described as infinite nothingness interrupted only by small islands of material that broke off from their native planes and occasional spinning columns of astral conduits (called wormholes or gates and resembling water spouts from a storm at sea).
The Astral plane connected the various Prime Material Planes with each other and to the first layers of all the Outer planes. Travel in the Astral was usually accomplished by spell, psionics, device, or color pool and involved leaving your physical body behind while your astral self traveled to your destination.
During this transit, a nearly unbreakable silver cord connected your astral self back to your physical body. When you arrived at another plane, a new physical body manifested out of local materials.
Wormholes linked specific places in the Outer planes to each other and to fixed locations in the Primes—quicker but likely more dangerous because your physical body was transported directly to a terminus that might be inhospitable or guarded.

Type

Dimensional plane

Location under

The Transitive Planes