Paraelemental Plane of Ooze
The Paraelemental Plane of Ooze was Inner Plane formed between the Elemental Planes of Earth and Water. The solidity of Earth combines with the fluidity of water to create a plane of muck and slime. Widely considered the most disgusting Inner Plane, the Paraplane of Ooze is avoided, often used as an interdimensional garbage dump. It is also used as a place to send people and things that are being punished, or are meant to never be found. Native creatures include ooze paraelementals, ooze mephits, the so-called ooze sprites, various kinds of slimes, oozes, insects, and other unsavory creatures.
In the Dark Sun world, this plane is replaced by the Paraelemental Plane of Silt.
In the early days of 1st Edition AD&D, the Paraelemental Plane of Vapor took the place of the Paraplane of Ooze.