U-Base

Mountaintop castle, tower near spawn, underwater base, some fairly extensive mineshafts. Not the prettiest but it was a lot of fun to make.

There is a Nether pathway between the underwater base and the castle. It's mostly protected from ghasts. Mostly.

I've been working in this world for a bit and some of the terrain is older, but there are some very interesting features that make it neat to explore.