Underwater safe haven is a large underwater area covered in glass on the ocean floor.
The purpose of this is that to have a safe retreat from the zombies

this map includes
1. one large underwater house
2. a small village on land with a port and a wall to keep the zombies out
3. a rich mine on the ocean floor
4. a tunnel leading from the land to the safe haven
I had left a lot of area empty so you guys can build whatever you want. If you don't like the underwater house feel free to destroy it and build another one.