The Sub-Zero Containment is a room on the Main Deck of the BSL Station in Metroid Fusion. As its name implies, it has a sub-zero temperature. Samus Aran will constantly take damage within it if she has not obtained the Varia Suit as a result of becoming a Metroid hybrid.
This room is notable for containing the Ridley clone's corpse from Metroid: Other M, preserved in ice. It was placed there by Galactic Federation personnel, but whether they were the same corrupt factions behind the BOTTLE SHIP incident or benevolent individuals who simply wished to seal it away, is unknown.
The Sub-Zero Containment can be entered early on in the game; the music within it is a mysterious, unsettling theme. To add to this tone, the camera has a sluggish horizontal pan when Samus reaches the blue gate inside, making for a slow, dramatic reveal of the room's main content. It is never confirmed if Samus can see the remains of Ridley's clone behind the gate, and she will not be able to get beyond it until after Nettori's widespread vines begin to choke the Reactor Silo. At that point, Samus is forced to take an alternate route to her gunship, where she will drop into the chamber from the ceiling on the other side. She witnesses the body's eyes glow red before an unshielded Core-X floats out of its chest, resulting in the frozen corpse collapsing in front of her. This X Parasite would travel to Sector 1 and transform into Neo-Ridley, a mimicry that Samus battles. To escape the room, there is a Pit Block in the floor just under Ridley's remains.
- Prior to the existence of Metroid: Other M, this room was a source of debate and speculation among fans of the Metroid series, as they struggled to unravel the reason(s) for the corpse's presence, which was believed to be the original Ridley back then.
- The Ridley clone's frozen corpse, along with the later rotten corpse mimicry, reuses the same sprite as the original Ridley from his prior appearance in Super Metroid.
- Interestingly, this room damages Samus at a slower pace than the sub-zero areas of Sector 5, likely to give players a chance to witness the frozen Ridley corpse, despite the few Energy Tanks they would have at such an early point in the game.