The Hibernation Chamber is a large room constructed by the Quintessons in the very depths of Cybertron during their rule of the mechanical planet. Placed in the lowest known levels of the machine world, the Hibernation Chamber appeared organic in construction and had large biological cocoons hooked to a machine where they were suspended above through cords.
These cocoons pulsed as they kept their occupants in a deep sleep. The Hibernation Chamber was used by the Quintessons to trap the most powerful Trans-Organics which they could not destroy and were to remain there for all of time.
A secondary larger chamber nearby, which was sealed, contained the beast known as the Dweller.
The Transformers cartoon
The Decepticons were informed by the Quintessons that an Autobot power core was located in the chamber. Travelling to the depths of Cybertron, they found the chamber only to learn that they were tricked. In Galvatron's anger, he damaged the hibernation cocoons which awakened the Trans-organics.
Galvatron, Cyclonus, Scourge and his Sweeps attempted to flee from the powerful Transorganics by destroying the door into another chamber. While inside, they quickly learnt they were not alone and unwittingly released the deadly Dweller; which was part of the Quintesson plan.