Here a new try:
https://drive.google.com/uc?export=down ... 2Q2V3lGVE0
I changed the origin from the boxes back in the middle and cropped the transparent from the water. It's much easier this way with the coordinates.
One thing doesn't work. If you push a box in the water when it's rising and there is a box already floating, you got funny side effects. The easiest way to avoid that is don't let the player push a box in the water when it's rise. <img src="{SMILIES_PATH}/icon_e_smile.gif" alt=":)" title="Smile">
I look if I could fix that, but I you didn't need pushing boxes in the water when it's rising, it should all work.