This elevator shaft is sealed by the Golden Statue, and cannot be accessed until four bosses are defeated. Instead, an elevator in the western parts of Crateria, which comprises the surface and top layers of Zebes, is its entry point. In Super Metroid, Tourian's location has changed, and it is no longer accessed through the upper areas of Brinstar. However, upon defeating Mother Brain, a time bomb is set, and Samus is required to flee through a long, upward escape shaft, leading to the surface of Zebes. Mother Brain, protected by five barriers of Zebetite, several turrets, and a constant barrage of Rinkas, is the final boss encountered by Samus in Tourian.
This is accomplished by freezing them with the Ice Beam and shooting them with Missiles. In Zero Mission, Metroids appear from the background, and must be exterminated before the next room can be accessed. In the original, Metroids are always visible in the foreground, and killing them is not required. While there are no Space Pirates in Metroid's Tourian, Zero Mission contains the bodies of dead Space Pirates, implying that they were killed by the Metroids. Throughout Tourian, Rinkas constantly appear to stall Samus's progress, implying a defense system.
Tourian is a series of long hallways with doors of various levels blocking the way, requiring the use of Missiles to proceed. After the barrier, an elevator leading down to Tourian can be accessed.
There, a barrier blocks the way, and it can only be opened by the defeat of Kraid and Ridley in their respective hideouts.
In both games, the entry point to Tourian is reached by ascending a tall shaft east of the staring point in Brinstar, and traveling westward from there. Though their maps vary to some extent, Metroid and Zero Mission feature comparable maps, with Tourian located in roughly the same place in both.