The black mouth of the tunnel was just above them.

She doesn't know where the mouth of the tunnel is.

Actually it could no longer be called a tunnel mouth.

A few feet away at the mouth of the tunnel, I stopped.

Finally, he put down the pick and went to the mouth of the tunnel.

He stood at the mouth of the tunnel, holding his free hand toward her.

He made out the black shape of another tunnel mouth.

The mouth of the tunnel looked very round and black as they came near.

Unless he was waiting just beyond the mouth of the tunnel.

Then he and Tom forced their way into the mouth of the tunnel.