Starting a new thread here to expand on this idea.
So I was chatting with Red51 on the water update and got an idea for lava tubes. I figured that since the "hell" world is basically like a giant air pocket between the mantle and the crust of Earth. This makes it seem more reasonable that "hell" is actually so deep below the surface because the Earth crust is only about 10 miles at its thickest! So I envisioned lava tubes coming up from hell. These tubes can be like cave structures going up with only a few branches reaching the surface. This should be the only reason why lava would be seen on the surface (unlike Minecraft where lava pools are random with no connection to the underworld.
These lava tubes should begin from below the lava level in hell so the lava would be pushed up the tubes and to the surface. From within hell, the tube should look like some kind of nasty hellish twisty trunk connecting the ceiling to the floor of hell to make it look scary. The inside of the lava tube could be lined with some kind of lava stone which can be mined. The lava stone would be a layer between stone and gravel and the actual lava itself. I also added a water pocket to lead to a spring on the surface. Any areas where flowing water and lava mix will create obsidean ofcourse.
Another idea with these lava trunks is that if you happen to be mining deep underground and you mine into lava then you know that you can potentially mine straight down and find a trunk where you could scale down from the outside. Currently when I enter hell, i either fly to the bottom or set up connecting ladders to reach the bottom (which looks as cheesy as floating blocks in Minecraft).
I created an illustration to better explain the idea to Red51 plus to +1 on his art skill!
Here's my illustration. I forgot to include the lava ocean currently in hell. Please excuse the inaccuracies