Transit Tunnel South
Transit Tunnel South is a room found in the subterranean level of Torvus Bog. It is very similar in structure to the other Transit Tunnels. It can only be reached once Samus obtains the Annihilator Beam to open the Gray Hatches, and Kinetic Orb Cannons shoot Samus inside it.
Inside the tunnel are multiple water currents that rise up and go down, and a Missile Expansion can be reached by going to the top of them. Before reaching the top, the currents' course of the water must be changed by the use of a Bomb Slot. Once they are correct, Samus can obtain the Missile Expansion.
Rooms in Metroid Prime 2: Echoes