The tunnels narrowed here, and there were no lights because they weren't supposed to be in use.

As he moved along cautiously, the tunnel slowly narrowed to a bottleneck.

If the tunnel narrowed just a few centimeters, they would be stuck here forever.

He seated himself on an outcrop just past the place where the tunnel narrowed.

Then the main tunnel narrowed, and the offshoots stopped.

Then the tunnel narrowed to such an extent that they had to walk single-file.

The tunnel narrowed and kinked again, then opened out into the next chamber.

The tunnel narrowed, funneling them into single file with Data in the lead.

The tunnel gradually narrowed until it was slightly over five feet high and three feet wide.

By now, the tunnels had narrowed and lowered overhead.