I see you are going to create an updated version. I have 4 recommendations.
1. Make the map higher, this map would be great to fly around with a plane mod.
2. Make the map bigger, there isn't much water space.
3. Make the underwater parts have different height levels. The underwater floor is just flat.
4. Try to make the outside parts of the map (not the real map) have the same water as the actual map. I have no clue how to do this, but it wouldn't be weird to noclip up and see just a border, which is how the map is right now.

Thanks for the great map!