Once you climb out of the swamp, turn around and walk to the front left corner of the ledge. Turn right 45 degrees and jump to the rock that seems like a slide.

From there, jump to the sloped ledge of the central rock structure.

Turn left and locate the opening in the left hand wall. Take a running jump to the ledge beneath the opening and if you accidentally land on the slide on the left of the ledge, immediately press Action to grab its edge. Then you can shimmy to the right and pull up onto the ledge.

Pull into the opening and drop down at the other side. Pick up the Small Medi Pack and throw the switch ONCE to drop a block from the ceiling onto the floor, back to the room with the two swinging burners. This will give you the access for the 2nd Secret. Climb back out and make your way back to the ledge above the swamp.