[Tannerone]

I am sure propane is handy for tunnel use. Since it is heavier than air is will fill the tunnels. Just be sure to be a couple 100 meters away when you flip the switch.

You will definitely find out where the tunnels go!

[NoCmpromiz]

Since it is heavier than air is will fill the tunnels.

And then there's that old standby calcium carbide and water, plop, plop, fizz, fizz.... Great for blasting those moles outta the ground...

(or your handy acetylene tank - same stuff... breaking that triple linked carbon bond releases more energy than burning propane.)

(Please tell me I'm not the only one who has played with this stuff...)