This secret is easy to get but also easy to miss. When the flying mutant (7) explodes, turn around and hang from the outside edge of the ledge. Let go and grab the ledge below.
Pull up and enter the passageway. The chime sounds for SECRET #1. Pick up a large medi pack and ammo for the magnums and Uzis (5-7).
Continue along the tunnel and climb up on the left.
Keep going to an opening in the floor where you can drop down into another hallway with gray and gold tiles. At one end of this hallway is a ledge above the big lava pool. (This is within jumping distance of the ledge you stood on previously, but by finding the secret, you avoided that jump.) There are chomping blades in the doorway, but you need not worry about them. Go the other way.
DARK MODE: Even with brightness adjusted, dark images on a light background can be hard to see. May I suggest a reputable dark mode browser extension, such as Dark Reader? (Download only from trusted sites, like darkreader.org or your browser's web store.)
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