In both games, this is a dead-end corridor accessible from the right side of the entrance shaft.
In Metroid, the corridor is constructed from multiple tilesets, including blue and circular near the entrance and white and black near the end. The initial room is a square chamber with three midair platforms and a pool of acid below, from which an infinite stream of Geegas spawns. There are two passages in the large wall to the right that lead to a secret second half of the chamber, with another small acid pool and three midair pillars above. An Energy Tank is found in between the pillars, in plain view. As is typical of item corridors, the ceiling above the item itself is made of small white tiles.
In Zero Mission, this room's appearance has been significantly changed. It can be accessed at any time, but the Energy Tank cannot now be obtained without the Speed Booster as it is covered by a Boost Block barrier. Similar to other rooms in the redesigned Kraid area, decaying ruins and large cactus-like plants can be seen in the background. Acid fills the entire room, including under dry land, although it is not dangerous if Samus has the Varia Suit. To collect it, Samus must start running from the entrance to the room until her Speed Booster activates. She will run down a slight incline and across a bridge of Pit Blocks over the acid, and must quickly Spin Jump off the bridge. If successful, she will penetrate the Boost Blocks and collect the tank. She can also Shinespark to the right from the top of the incline. Four Reos are found above the bridge and will swarm Samus as she moves, but they are easily killed by the Speed Booster. After obtaining the tank, Samus can shoot a red button above her to call a zip line to her side, and ride it back to dry land.
- 4 Reos
- Energy Tank
- See above.
- 012 BIG WALL, SMALL PASSAGE (pg. 131)
- "The second corridor on the right ends abruptly with a thick, blue wall. When you stand on the ledge that extends from the wall and fire your Wave Beam to the right, you'll break a series of blocks and expose a tight passage that runs through the wall. Roll up and use a Bomb to blast yourself up to the height of the passage. Then roll to the right and collect an Energy Tank."
- 106 energy tank (pg. 45)
- "Speed is the key to collecting the lair's Energy Tank. Start running as soon as you enter the corridor. The Speed Booster will charge up as you reach the breakaway blocks. When you arrive at the end of the runway, jump. You'll fly into a wall of blocks that break under the influence of the Speed Booster, and you'll gain access to the tank."
- 012 BIG WALL, SMALL PASSAGE (pg. 108)
- "The second corridor on the right ends abruptly with a thick blue wall. When you stand on the ledge that extends from the wall and fire your beam to the right, you'll break a block and expose a passage that runs through the wall. Roll up and use a bomb to blast yourself up into the passage. Then roll to the right and collect an Energy Tank."