Like much of Brinstar, Corridor No. 4 features a mixture of blue rocky territory and mechanical structures suspended over acid. Interestingly, the blue rocks found exclusively in Corridor No. 4 are darker and rounder than those found in the rest of Brinstar; this is also seen in the background of Corridor No. 4 in Zero Mission. In Metroid, a small section of the fifth room contains orange terrain like that seen in Corridor No. 5.
In the remake, Metroid: Zero Mission, the rooms are more developed. The third room in particular has been overhauled, now featuring Mellow hives. The Zoomers and Wavers that previously inhabited the fifth room are replaced with Skrees, and there are now walls of Fake Blocks that must be shot to proceed. If Samus has not killed the Charge Beam Beast yet, it will confront her again at the entrance to the fifth room.
In Metroid, bombing the floor in the fourth room of Corridor No. 4 will drop Samus Aran through fake acid and into a vertical shaft, leading her to another room containing the Ice Beam. However, attempting to do the same in the second room will trap Samus in a shaft full of Rippers and Wavers, which is very difficult to escape from without using the Ice Beam. In Zero Mission, the fourth room only leads to a Chozo Statue that guides players to the Ice Beam's location in Norfair. Mercifully, the shaft underneath the second room is no longer difficult to escape from, and now includes a Missile Expansion.
Metroid: Zero MissionEdit
- Energy Tank
- In both games, lying on a pedestal above an acid pit in the fifth room.
- Missile Tank
- Zero Mission only. The first tank can be found in the shaft underneath the second room, contained behind a Bomb Block. The second tank can be found in the third room, in a hidden alcove containing one of the Mellow hives. The third can be found in the fourth room, hidden at the base of a wall of Fake Blocks.
- Charge Beam
- Zero Mission only, and only if the Charge Beam Beast has not been previously defeated in Corridor No. 5. Killing the Charge Beam Beast rewards Samus with the Charge Beam, which floats in midair.
- Although the yellow liquid seen in Corridor No. 4 is canonically considered acid, the NES manual refers to it as water, and this is reflected in various adaptations of the first game.
- In Victory Techniques for Metroid, Samus is exploring Corridor No. 4 when she is attacked by Wavers and knocked into the deadly water below. After escaping the Wavers, Samus acquires the Energy Tank found in this corridor. Later, she returns to Corridor No. 4 and bombs the floor, falling into the shaft leading to the Ice Beam.
- In the Captain N: The Game Master comic Money Changes Everything, Kevin and his teammates navigate a Brinstar cavern full of lethal water and Wavers. This description best matches Corridor No. 4, and therefore is possibly intended as a faithful depiction of this room.