This Mountain is nearly completely hollow. You spawn right at the top of it and if you make your way inside you can see its practically all empty space and lush cave. There is also a deep dark and an ancient city all the way down it including a mineshaft 🙂
There is probably way more but its so massive to check everything you should check it out yourself. The mountains are also pretty much at terrain limit roughly Y=256 in fact its so high the flat land you see inside is still above sea level pretty cool 🙂
by Sz_Entity