The Edge of A Large Pit                                -      N      - 
(-------------------------------------------------)     W <---(M)---> E
                                                        -      -      -

You are walking through a huge chamber somewhere beneath the surface of
the world.  There is a large pit to the east, and at the bottom you can see
a tunnel leading even deeper into the ground.  The edges of the pit are very
steep, but there is a small trail running down along the edge from here that
was not visible from any other perspective.