Maaaan.
I was just lost in some caves for four hours.
I finally got sick of wandering and escaped by using my four stacks of trunk logs that I had from before I went down to make ladders, and digging STRAIGHT UP. Made barely a loving stack of iron, but five stacks of coal.
Pretty awesome though. I found pits that I couldn't see to the bottom of when I set lava flowing down them, and one tunnel that went perfectly straight 3x3 shape for over 40 tiles with no irregularities in the walls.
Now I'm considering looking for a good place to make my home. Thinking I'll set up a big irrigation system for the farm out front, utilizing an artificial waterfall, and live behind said waterfall.