The Impact Crater is the last area Samus must explore on Tallon IV. It contains an endless amount of Fission Metroids, Phazon-mutated Metroids that are immune to most weaponry and can multiply themselves; a more hazardous red-colored variation of Phazon, which can kill Samus in seconds even through her Phazon Suit; and most notably, the eponymous antagonist of Metroid Prime, a Metroid that has grown to enormous size due to intense amounts of Phazon exposure.
The Impact Crater is the smallest area in the game, as it consists of only twelve rooms, which can be divided into two sub-areas: the Upper Caves, which contain the elevator to the Artifact Temple, and Metroid Prime's abode, where Metroid Prime is fought.
