Dooors2 Level 20 Walkthrough:
1. Press on the panels on the ground that the arrows are pointing to to open it. Pick up the goggles.
Select the goggles and use it on the water.
2. Use the brush on the wall underwater to see the clue. The fish shows you the clue:
Long, short, long, none, long, short.
Go back up and press the blue buttons to match the length of the fish's bones.
Press the buttons from left to right:
2 times, 1 time, 2 times, 0 times, 2 times, 1 time
Press the door to open it.