Okay. I misunderstood.
These are great suggestions.
The first two look great. I'll definitely try those. The next two are a little iffy. Those probably only look right from above. The last are already used in the second area (=blue dungeon) so they are already associated with the water. The blue area will be positioned before the green dungeon. I do really like the idea of them opening like that so I'll save those for a later date. I already had somewhat simular planned, but these will add brilliantly.
...
I'll try it out. Thanks for the input!
Btw: There is a secundairy area with random holes in the wall. I might as well post it below since people are interested. The red indicates how the blocks need to be moved, but that will be removed later on. It's just there for me as reminder of how to program it later on. Any comments on these rooms. These holes are purely for decoration. They had a function but that got scrapped. These two rooms are connected.
------------------
Edit: Here is the revised room.