Anyone know of a reliable way of navigating these things? I've thought about using trails of redstone dust, but it seems a bit labour intensive and won't help much with irregular vertical spaces. I got turned around twice and it took me near to an hour to find my way back out again.
When I don't know how to get back through the tunnels, I usually just dig upwards until I get to the surface
I sometimes use signs to indicate which direction I went when there was a split in the tunnel. I've also started to wall off sections that I don't yet want to explore. I leave a thin opening so I can see it's not a mob spawner later on.