That room, like Joe's cell, was a low underground cavern.

The council isn't building the nuclear submarine or the underground cavern itself.

This can lead to the development of large underground caverns that finally cave in.

The people in the keep must have thought all the underground caverns were destroyed.

All she knew was that within an underground cavern, such a danger cry could only mean one thing.

Once up, no one would ever realize it was the entrance to an underground cavern.

The river can sometimes run through deep wide underground caverns.

The strange company finally came out into a huge underground cavern.

He gestured with his free arm at the underground caverns.

Murphy could not see the length of the underground cavern.