The Hydro Access Tunnel is a room in the underwater Frigate Orpheon, located in Tallon Overworld in the game Metroid Prime. The room consists mainly of a Morph Ball tunnel. There is an Energy Tank located on the upper left of the room.
While this room is part of the Frigate, it cannot be visited until after the crash landing in Tallon Overworld. Since the crash, the platform of the elevator has been destroyed, so the room is now accessible. The location of the door connecting to the elevator is at the bottom of the shaft. This room could also quite possibly be the elevator machine room for the connection elevator to deck beta. "Hydro" sometimes means "Hydraulic". As in a hydraulic elevator.