: Thanks! That's changed things, but I'm still unable to get past the half-door
: leading to the key in the water. Also, at the top of the hidden stairway
: by one of the face doors, there's another half-door. Still stuck. I found
: the "L" switch at the top of the pillar but it doesn't seem to
: do much that I can tell. I've fired off all my grenades at it and a few
: SPNKR rounds for good measure.
It'll turn red (or gray out) if you hit it.
Next, you need to go back down to the outer ring in the 'canyon'. Remember the teleporter down there? Go back through it and look around again.