The Hydro Access Tunnel is a room in the underwater Frigate Orpheon, located in the Tallon Overworld. It appears in Metroid Prime. The room is mostly 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 on Tallon Overworld. During said crash, the elevator itself in the adjacent Connection Elevator to Deck Beta crashed into the bottom of the room, and was destroyed. As a result, the room is now accessible. The location of the door connecting to the elevator shaft is at the bottom of the shaft, below where the elevator was programmed to travel.
- If Samus enters this room on the Great Tree Hall side, and if she looks up facing the tunnel, she will see a part of the outer hull of the Frigate itself. This likely means that this was a different room before the crash, and when the Frigate crashed, it broke through the original room, crushing it, making it another entrance into the flooded vessel.