The River                                              -      -     NE 
(-------------------------------------------------)     W <---(M)---> -
                                                        -      -      -

You are being pulled quickly along by the current of this rushing river
that roars between high banks in the midst of the woods.  The banks are
sheer and steep cliffs, and there seems no way to climb them without help
even if the current lessened to a point where you could reach them.  Rocks
jut up from the water, taking all your skill to avoid as you are carried
past, and once in a while a floating branch or log hits you from behind.  
     A small brown rock has been smoothed by the current.
A large boulder crashes down from above and shatters directly behind you!