Screw Attack Underwater Glitch
From M2K2: Metroid Prime 2 Wiki
I was messing around in the third room in torvus bog, when i did a screw attack from the dark beam door to the main section of the room, and there was air underwater. i could screw attack and everything, but i went into morphball, and when the camera went back under the water-line, everything was back to normal again. I have not been able to reproduce this glitch.