[quote=@BBeast]
Vakarlon and Mammon have already made tunnels of various sorts, so you can adopt those.
[/quote]

The Submaterium labyrinth is confirmed to be spacially anomalous, at that. You can get from the Galbar tunnels to the Mirus tunnels by walking.

Just... Don't get eaten by demons or kidnapped by Heartworm, is the thing.