In both appearances, Corridor No. 2 leads to the entrance to Tourian.
In the original game, it is a long corridor composed of the blue rock that makes up most of Brinstar, with several Koma statues, a small acid pool in the center right, and Air Holes that spawn yellow or red Zebs. At the end of the hallway is a Red Hatch which leads to the Tourian access room.
While Samus can visit Corridor No. 2 very early on during her mission, she is normally unable to enter Tourian until defeating Kraid and Ridley. In Metroid, a Reo can be lured from this corridor into the entrance room, frozen between where the bridge should appear (when both bosses are defeated) and the acid, and then jumped or Bomb Jumped off of, which allows Samus to access Tourian faster and without defeating Kraid or Ridley.
Zero Mission greatly expands the room and connects through the ground to the corridor leading to the Long Beam, which is directly under this room in the original Metroid. It is through this entrance that Samus first enters this room. There are two extra acid pools, with floating platforms above two of them and another platform in the center of the room, above the lower entrance tunnel. An enclosed area with a massive purple boulder in the background is present on the right. Two unknown structures can be seen installed into the ceiling here as well.
After stepping into the entrance room and returning, the doors lock. When Samus enters the enclosed area, she is confronted by a Dessgeega. Killing it is the only way to unlock the doors. The doors lock again when Samus re-enters this room after defeating Kraid and Ridley, forcing her onward to Tourian.
- Blue-tinted shaft (via Blue Door)
- Entrance to Tourian (via Red Hatch in Metroid, Blue Door in Zero Mission)
- "Cave shaft" (Zero Mission, via tunnel)
- 010 HATCH AN ESCAPE PLAN (page 30)
- "If you run to the right after you reach Norfair's[sic] upper-left region, you'll find a hatch that will not open, no matter how long you blast it. Run to the left to discover the two-headed statue that blocks the way to Tourian, then return to the hatch.
- A spiderlike creature will drop from the ceiling, causing major damage on contact. Fire at the enemy using rapidly repeated beam blasts. After your victory the hatch will flash, indicating that you can shoot it open."
- In Victory Techniques for Metroid, Samus waits until defeating Ridley and Kraid before traveling through Corridor No. 2. She recommends that players farm the Zebs for energy before entering Tourian.