tunneling

For centuries, people have been tunneling into the landscape, which proved especially adept at hiding those fleeing persecution.

They considered tunneling in from the side or maybe creating an entry hole by placing a shaped charge on the shelter roof.

Tunneling mud-banks under water, with streams of water or streams of compressed air, struck me as decidedly a novelty.

Here the stream which has done all this carving and tunneling has got to the end of its tether.