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The "acidic concourse" is a room in Kraid's Lair/Kraid. It appears, with significant differences between versions, in Metroid and Metroid: Zero Mission.


In both games, this is a corridor accessible from the left side of the entrance shaft, which leads into a vertical shaft with fake acid.

In Metroid, the corridor is constructed from blue bricks and tiles. It is long and has five Air Holes in the floor, as well as three thin acid pools. A large portion of the floor in the center of the room is raised; three of the Air Holes are found here. The room is infested with Sidehoppers, which makes navigation difficult unless Samus has the Screw Attack. Near the left side of the room are three metal pillars, one in the floor and two hanging from the ceiling. This is one of two corridors Samus can take to reach the lair's leftmost shaft.

In Zero Mission, this room's appearance has been significantly changed. It is now constructed from solid purple material and partially submerged in acid. As with other rooms in Kraid, cacti and ruins can be seen in the background. Under normal circumstances, Samus cannot get through this room without first activating the ancient Chozo machine to energize the zip lines in the lair. Upon entry, she is greeted by a short wall in front of her with a tunnel above it blocked by two Fake Blocks. Destroying these, and a subsequent block after allows her into a short, zizagging tunnel leading to the rest of the room. Here, only four parts of the walkway are above acid level, and the fourth cannot be reached without the zip line above. As Samus is using it, she must shoot five Fake Blocks in her way to avoid being knocked down. Alternatively, she can Bomb Jump up to the zip line and attach her Morph Ball to it. It will then take her over the blocks entirely and drop her off on the other side.

It is possible to get through this room without using the zip line, but it is much more difficult. Samus must carefully jump to the first midair block with her Power Grip, roll atop it, then quickly roll off, unmorph and grab onto the next one. On the last block, she must propel herself off using a Bomb to get over the ledge before the exit. A demonstration can be viewed here.

Connecting rooms[]



There are no enemies in this room in Zero Mission.


MZM Kraid's Lair Missile Tank 9.gif
Missile Tank (Zero Mission)
Requires Gravity Suit and Speed Booster. This tank is found in the acid. The Gravity Suit is necessary to obtain it, since it allows Samus to move freely in liquid environments. Samus must drop into the center of the acid (between two platforms above it) and shoot through Fake Blocks in her way. She must then run to the right until her Speed Booster activates, over a slope and quickly Ballspark through a short tunnel to the right. This will take her to the tank. To exit, she can either return the way she came or activate her Speed Booster again, then Ballspark up through part of the tunnel. This takes her back to the entrance of the room.

Official data[]

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

084 SCOOT AND SHOOT (pg. 46)
"On your journey to the lair's middle-left area, you'll navigate a tight passage in Morph Ball form then reach an apparatus that will carry you over a lava [sic] pool. Fire steadily as you cross to clear the area of floating blocks."