You could, I suppose, include train tunnels--Keaton's OUR HOSPITALITY;
THE LADY VANISHES (where the tunnel creates a clue); and of course
MISSION IMPOSSIBLE's ending in the Chunnel (or for that matter, SPEED's
climax in the unfinished LA subway) are all examples.
 
I don't recall if anyone has mentioned the film version(s) of Jules Verne's
JOURNEY TO THE CENTER OF THE EARTH.
 
Speaking of Verne, Melies has his astronauts enter a sublunar tunnel in
A TRIP TO THE MOON.
 
Don Larsson, Mankato State U (MN)
 
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