At the Bottom of A Pit                                 -      -      - 
(-------------------------------------------------)     W <---(M)---> -
                                                        -      -      -

At this point the tunnel begins sloping upwards 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 up
eventually.