How to Dig Underground Tunnels

Plan out the length, width, height and path of your tunnel and check with the local utility companies to make sure you won't be digging where wires or pipe have been laid.

Dig a vertical shaft to start your tunnel. This shaft should be three times the height of your tunnel. If your tunnel is going to be six feet in height, you'll have to dig down 18 feet to ensure the ground above the tunnel is stable enough to be walked on. It should also be at least three feet square so there's room to maneuver equipment in and out of the tunnel.

Tie a piece of rope around a bucket and have one of your friends help you haul dirt out of the hole. It will become apparent after digging down about six feet that it's easier to take the dirt out with a bucket than to try to throw it up out of the hole.

Start the horizontal part of the tunnel when you've reached the end of the vertical shaft dig. Once you've removed enough dirt to form a doorway, frame it in with 2x4s. These should be cut to size at the surface and then nailed together in the shaft itself. This can be done by toenailing a simple rectangular box structure in the opening.

Dig further into the tunnel. Every four feet, install another 2x4 brace (shoring). If the dirt in the ceiling of the tunnel is loose, you may want to consider a plastic tarp or plywood ceiling. This usually isn't necessary as the soil at these deeper levels is usually quite compact.

Put on a headlamp when you start to have trouble seeing in the shaft. Headlamps are far superior to flashlights, lanterns, candles or other types of illumination.

Run a flexible pipe down into the horizontal shaft and place a fan at the open end of the tunnel to blow fresh air in. Stagnant air will build up in the tunnel and cause the oxygen level to diminish rapidly.

Remove any large rocks or earth that's hard to strike through by breaking through it with a pick ax. If you're unable to remove an obstacle, you may have to reroute your tunnel.