To test the latest beta I decided to take the same seed I’ve been playing for a few years now and open a fresh instance. At first all was fascinating to see where the new version differed from my original, lakes and rivers where there were none before, changed shorelines, strange water filled holes leading into the depths.  This is where I noticed a problem, I could not find any caves leading downwards suitable for caving. All of the ones from my original seed Were no longer there, either just not there or replaced by split hills or deep wide aquifers that would be impossible for me to traverse since it was early game and I had no means to breathe underwater. In addition once I got to mining I encountered no open air caverns, only water ones if any, until deep into the world. Maybe it was my spawn point but it would seem that there should be a better mix of open air and water caves. The current mix still needs tweaking