Subterranean gets its name from its traits: it is the farthest room away from the general area of Arcterra, and it has a bottom floor. Upon Samus' first entrance, the room is a confusing maze of Force Fields. Her ultimate goal here is to get to the center of the room, which features an inactive elevator. To activate it, Samus must search around the ceiling of the room to find three red crystal switches. The catch with these particular ones is, if Samus is too close, they will close up. When fired at, the lift will activate, and Samus must navigate to the center. This is difficult, as the Subterranean's maze of Force Fields acts similar to a hall of mirrors. Samus must even jump atop a Force Field to get to the center.
Samus, when she has reached the elevator, can automatically ride it down and access another floor. From the initial hallway, there is a branch-off made of ice. Samus then reaches a fork in the road. On the left, she is attacked by an Alimbic Turret, v2.7, wielding the powerful Imperialist, and she must defeat it, preferably using her own Imperialist. Destroying it releases a Shield Key that lowers an Artifact Shield blocking access to the Cartograph Artifact for the second Stronghold Void on Arcterra. Collecting the Artifact will disable a Force Field just behind the Artifact's former location.
Shortly after Samus returns to the top floor of Subterranean, all Force Fields disappear. However, a horde of at least eight Guardians appear, and attack Samus. After she destroys them all, she is permitted to leave.
- Alimbic War 04
- "GOREA DEVOURED OUR PEOPLE'S LIFE ENERGY AND GREW POWERFUL FROM IT. DEATH SWEPT ACROSS OUR WORLDS, AND WE DESPAIRED."
- Alimbic War 11
- "TO CONTAIN GOREA, OUR PEOPLE REDUCED THEMSELVES TO PURE TELEPATHIC ENERGY THROUGH THE PROCESS OF ESSENCE TRANSFERENCE."
- Alimbic War 05
- "WE FEARED NOT ONLY THE EXTINCTION OF OUR RACE, BUT THE POSSIBILITY THAT THE EVIL WOULD SWEEP THE GALAXY, ANNIHILATING ALL IN ITS PATH."