Damp Tunnel                                            -      N      - 
(-------------------------------------------------)     - <---(M)---> -
                                                        -      #      -

This tunnel is quite small, and you are forced to stoop down in order to
walk through it.  The air is heavy with moisture, making it rather hard to
breathe.  You also notice the thin trickles of water running across the
floor make it difficult to walk without slipping.  The tunnel is
unobstructed to the north, but to the south there is a large pile of stones
blocking our way.  Perhaps with a bit of effort it would be possible to move
them out of the way.