Tarterus

The plane of Tarterus is located between chaotic evil and neutral evil in alignment. Each known layer of Tarterus is described as a chain of glowing scarlet orbs stretching into infinity. Each orb of the top layer is the size of a Prime Material world and the orbs get smaller with each successive layer. The orbs of the "inner" layers can be imagined as nesting within the orbs of the "outer" layers like Matryoshka dolls.
Tarterus has no native pantheons or members of the Faerunian Pantheon residing there, though some say that in the depths of Tarterus lies Carceri, the Prison, where the corrupted god Moander is chained.

Location under

The Astral Sea