This is the fourth and final battle within the subchambers of the crater, where Metroid Prime in its exoskeleton form is fought. In this subchamber, Metroid Prime will use all four beam color attacks, randomly switching between them at will, making it more difficult to cause damage quickly. When damaged enough, it will break through a wall, falls through Subchamber 5 and all the way down into the Metroid Prime Lair.
In the NTSC version of the game, three tunnel grooves exist in the ground that allow Samus to avoid Metroid Prime when it runs across the room, but in the PAL and Wii versions, all but the middle groove have been removed.
- If one looks up at the roof towards the hole to Subchamber 3 where Samus and Metroid Prime initially dropped down from, they will notice it is mysteriously blocked by a wall of Red Phazon. How this was formed remains a mystery, however it is possible some kind of avalanche occurred after Samus fell through the hole. It was most likely placed there as a means to prevent escape during battle.