The 4 colored keys

Key 1 – If you use the yellow rope in the back of the

gray tube goes fishing then you catch the 1st key.

Key 2 – If you push the small tube through the tube on the inside of the box, the 2nd key will come out.

Key 3 – Under the double bottom you will find a wooden box, which contains key number 3.

Key 4 – The last key is in the large lock at the back. By following the nail sign with the red rope you get key number 4.