Such a great way to start off with the RP Xanatos.  Detailed and believable.  Some 20+ years ago I went through the Carlsbad Caverns.  Was very much like what you described without the glowing part.  They had lighted areas of course which would have given the same effect though. At one point in the tour they shut off all the lights in one particular place in the cavern dropping us into complete pitch darkness.  It was the eeriest feeling I have ever had in my life.  And the silence as you said was deafening.  Very good job my friend.