|--|______________|
            |--| |__________| |
            |--|_|          |_|
            |                 |
            |_               _|
              |_           _|
                |_       X|   <--  X is the staircase...
                  |_   _|
                    |_|

-------------------------------------------------------
Step 2.
  After getting to where you can see only water, follow the
instructions below.  I tried to eliminate most turnings to
minimize mistakes:

 Go left until you stop  (  -->examing water movement)
 -> down 3 steps  (  -->push down button 3 times)
 -> Left 1 step.
 -> Up until you stop
 -> Left until you stop.
 -> Up until you stop.
 -> Right 1 step.
 -> Up 4 steps.
 -> Right 3 steps.
Now, if you:
 1. Go up until you stop: you'll enter a room with air, and a treasure box is
    hidden in the water below.
 2. Go down until you stop: you'll get to the next floor.

Continuing 2:
 -> In that new floor, go straight down to the end.  (It takes a while)
 -> Go Right until you stop, and you should get to a new floor again.
 -> In the new floor, go left 2 steps.
 -> Go up until you stop.
 -> Right 2 steps.
Now, if you:
 3. Go right one step, and you can open a treasure box in front of you.
 4. Go further up until the end, and you're out! (Almost)

----------------------------------------------------------------------------
Step 3.
  In that last floor, you can't just go straight down because that's where the
staircase leads you back to the previous floor (the direction problem), so you
need to make a big turn-around.  Make it by turning right, not left, for there's a
hole somewhere on the path to left and could drop you to the previous floor.
  You can try press 2 or 3 to eliminate that water layer anyway.