***** Sewers (level 2) *****

                           narrow ledge
                         *------*------*        1 - path in UnderDark 
                         |      |      |        2 - swewers drain (level 3)
                        n|      #      v        3 - pit (level 1)
                        a*--#       #--*        4 - shaft (level 1)
                        r|      M      |l       5 - dark pit (level 1)
                        r|      i      ve       6 - cave entrance(level 3)
                        o*--#   d   #--*d
  under                 w|             |g
  mudhole                |      A      ve
   *------------*       l*--#   i   #--*
                |       e|      r      |     4   
                |       d|             v    /      
                |       g*--#   #   #--*---*
                |       e|  led |ge    |
                |        *------*------*
                |       /|      |
under           |      1 |      *
dark 5          |        |     /      3
pit /           |     odd|    2   un /der
   *------------*--------*----------*
  /                 intersection    pit
 6