Early Sanctuary Fortress from first GFMC Compound Visit
From M2K2: Metroid Prime 2 Wiki
Using the technique from the 101% Collection Rate diddy, in the GFMC Compound early in the game, you can go to the Sanctuary Fortress door instead of getting the missile launcher and activating the cut-scene.
The gate blocking the door isn't there, so you can just go through it. You can't get very far, though.
-tjp7154
