Carlsbad Grotto to be exact. I'm trying to get to the yellow key, but I
can't find a switch or door combination to make the wall vanish.
help-Help-HELP!
yes, awful design on my part, I'm sorry about that. But in the same room as the key, see that enclosed corridor? You have to go inside of it from another angle. Once you're inside the enclosed corridor, shoot down into the water until you break a switch, that'll unlock the key for you.