A Sloping Shoreline                                    -      -     NE 
(-------------------------------------------------)     - <---(M)---> E
                                                        SW     S      -

You are standing on the edge of an enormous underground lake.  The ground
rises out of the water at a forty-five degree angle here, leveling off to
the southwest into a large cavern.  You can't see much of anything around
you through the darkness, but you hear an occasional splashing sound coming
from the lake.