The Morass (The Crimson Hand)

The Morass was an alternate dimension, inhabited by the Reapers and the Chronovores and resembling a red vortex. It was also where the Manus Maleficus originated from. After Majenta Pryce used the Manus Maleficus to destroy the Crimson Hand, the Maleficus returned to the Morass. The Doctor briefly entered the Morass with the Maleficus, before he used it to save Majenta. (TV: The Crimson Hand)