You might want to ask the people who got stuck in the Chunnel first. And that's only a short tunnel (26mi?) under the English Channel.

I was sitting in a pub in Brighton the day the Chunnel opened many years ago, watching all the hoopla on the TV over the bar. There was a reporter asking the Britts on site what they thought about now being connected by road directly to France.

One guy said, "Well I don't think it's a good idea." The reporter asked him, "Why, don't you like France?" He said, "I LOVE France, it's the French I hate!"

Classic!