The work on our house has been going on for months, but we're finally starting to see a 'light at the end of the tunnel'.
The prisoners tried to 'tunnel' their way out. [=tried to escape by digging a tunnel]
His 'tunnel vision' made sensible discussions on political issues nearly impossible.
(..) Are you saying there's another way into Mordor? Yes. There's a path... ...and some stairs. And then... ...a tunnel. He's led us this far, Sam. Mr. Frodo, no. He's been true to his word. No. Lead the way, Sm'agol. (..)2002 The Lord of the Rings: The Two Towers