In both games, this is a tall vertical shaft on the upper right side of the lair, which connects to four corridors.
In Metroid, this room is optional and does not need to be explored. It does not lead to any expansions, or more importantly, Kraid. It is constructed from white brick tiles and black rock tiles, with green bushes growing out of the walls. The shaft is ascended using multiple midair blocks and ledges mounted on the walls, many of them containing Zeelas. There are four doors on the left side of the shaft, including the entrance. The upper three lead into identical corridors.
In Zero Mission, the room serves a greater purpose and under the normal sequence of events is one of the first rooms visited in Kraid. Parts of it are now sealed off. It is shorter in length, but still connects to the same four (changed) rooms as the original game. The tiles are still mostly grey, but more rectangular in shape, and much of the walls are now a dark blue. There are fewer bushes growing from the walls, and they now have pustules. The initial room is a short shaft with four platforms leading up to the ceiling, and a glass tube to the right. Beside this tube is a headstone with an etching depicting a ball being propelled upward. This is a hint to a Morph Ball launcher in the ground, accessible by laying a Bomb directly underneath the stone.
Using the launcher in Morph Ball form propels Samus up through the glass tube to the top. The tube is filled with six Rippers, all of which are killed when Samus collides with them. The force of her hitting the underside of a midair wall is enough to knock two Zeelas off their perches above. Samus will then land in a short tunnel. After climbing out, she finds a wall on the left and the midair wall she collided with on the right, each with two alcoves for her to jump to using her Power Grip. The last alcove has a Fake Block in it, which can be removed with a beam shot. Samus can then climb to the top of the shaft, to be able to access the room with the ancient Chozo machine. The second and third doors are found below the uppermost door, but the second highest can only be entered from the machine's room. A Pit Block underneath the door to that room drops Samus to the third door, which leads toward the Acid Worm's room.
- "Caged Sidehopper hall" (via Blue Door)
- "Kraid's highest corridor" (via Blue Door)
- "Chozo machine hall" (Metroid, via Blue Door)
- "Save Room 2" (Zero Mission, via Blue Door)
- "Acid Worm's room" (Metroid, via Blue Door)
- "Worm access" (Zero Mission, via Blue Door)
- 10 Zeelas
- 7 Zeelas
- 6 Rippers
- Missile Tank (Zero Mission)
- After launching herself through the glass tube, Samus can climb into a narrow tunnel beside her to reach this tank. If she falls off the ledge where the item is, she will drop through a Pit Block below.
- 073 ROCKET CLIMB (pg. 44)
- "When you reach the shaft at the right edge of the lair, plant a bomb to the left of the tall tube to clear the way to a launcher at the bottom of the shaft. Roll into the launcher, then plant a bomb. You'll take off for a point in the middle of the shaft. As you begin to fall, press Right or Left to drop onto a ledge."
- 074 ZIG ZAG CLIMB (pg. 45)
- "Two walls with alternating ledges face each other. Clear away the enemies in the area, then jump from ledge to ledge to ascend. When you reach the last open ledge, fire up and to the left to open access to another ledge."
- 07 RUN RIGHT, RUN LEFT (pg. 45)
- "After you cross the lava [sic] and record your progress, run into the main shaft. You'll fall from one blue hatch to another. Open the new hatch and enter the next area."
- 083 missile tank (pg. 46)
- "On you way down the region's right-hand shaft, drop into the narrow passage and press Left to catch the next left edge or to roll into the path if you're in Morph Ball form. It leads to a Missile Tank."