A Sloping Shoreline                                    -      N      - 
(-------------------------------------------------)     W <---(M)---> E
                                                        -      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 south and the west 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.