Cork

I made it into the lair of the eyeless. But I had to leave to get more camping supplies. Now I can't get back to the lair of the eyeless. Can I get back in some how? Any help would be greatly appreciated.

I cannot get into the secret room on this level. I'm in scouting mode and everything else shows up but the switch on the wall to open the secret door. Am I missing something do I need to accomplish something first?