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The "chain reaction chamber" is a room in Ridley. It appears in Metroid: Zero Mission. It did not exist in Metroid.


This is a new room in Ridley found within the right wall of the lair's rightmost shaft. To enter it, Samus must build up her Speed Booster in the Zebbo Nest, Shinespark toward the sloped floor in the subsequent Save Room, and quickly jump up to a midair platform in the shaft, then finally Shinespark into the wall on the right. Doing that leads to a passage into this room. If the Speed Booster has been skipped, likely on Low Percent Runs, then it is impossible to visit this room.

The chamber is devoid of enemies. Initially, it appears as a corridor with a low-hanging ceiling and a pillar hanging near the right end. Samus must run from the hidden passage in the previous room into this chamber until her Speed Booster activates, crouch to enable a Shinespark, quickly roll underneath the pillar and Shinespark up. At the top, she must grab the ledge next to her and pull herself above it, entering Morph Ball mode in the process. Samus must lay a Bomb to destroy a block beside her. This begins a chain reaction of a series of Bomb Blocks rapidly exploding. The explosion leaves two pillars, including one in front of the Missile Tank itself, and a small midair duo of two blocks that are Pit Blocks with delayed crumbling. The entire floor below is made of Pit Blocks, which means that if Samus falls through them, she must start the puzzle over.

While the Space Jump helps in obtaining the tank, Samus can collect it without the upgrade providing she carefully navigates the line of Bomb Blocks as they explode with the help of her Power Grip and by Wall Jumping. Once Samus reaches the pillar in front of the Missile Tank and scales it, she can drop down to obtain the tank. Underneath it is a Pit Block that she can drop through to reach the entrance.

A demonstration of obtaining the Missile without the Space Jump can be seen here.

Connecting rooms[]


Missile Tank
See above.

Official data[]

Metroid: Zero Mission: The Official Nintendo Player's Guide[]

"Travel to the lowest corridor. [Zebbo Nest] Run rightward in the even passage near the ceiling to build up your booster, kneel to stop, then scurry over to the save room. Fire at the right hatch and blast off to the right, hitting the uphill slope as you go.
Kneel to stop at the bottom of the shaft. Quickly climb up to the next hatch, tap the A Button, then hold Right to blaze through the right wall into an unmapped section."
292 missile tank (pg. 93)
"Run right and kneel to stop before you hit the dangling pipe. Roll under the pipe, straighten out to a standing position, then blast off. Grip the ledge when you reach the top.
Detonate a bomb in the upper-right corner to start a chain reaction. Move left as you drop, and roll under the solid pipe. Straighten and jump up before the floor gives way.
Use the Space Jump technique to hover while most of the blocks in the area break apart. Then fly to the left, grab the top of the pipe, roll left and drop to a Missile Tank."

As stated, the Space Jump is not required to obtain the Missile Tank, but it may assist.