Above A Pit                                            -      -      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      -      -

At this point the tunnel begins sloping downwards so quickly that it
almost forms a vertical cliff.  There is a rough path worn along the side of
the slope, with hand and footholes carved in at random intervals.  While it
might be a slightly dangerous endeavor, you should be able to climb down
eventually.