Crossing the great river, buried in water

I’ve been looking at the Cabot Strait a lot lately, mainly because I think a tunnel under the Strait of Belle Isle doesn’t make a lot of sense compared to one across the Cabot.  The tunnel would almost certainly proceed from Port aux Basques via St. Paul Island  and thence to the Cape Breton headland (you could probably even build a bridge that far).  You’d probably put rail service in the tunnel, because nobody in their right mind wants to drive an hour under a half-klick (in places) of water.  

It would be an epic feat of engineering (similar to the Bohai tunnel) with massive benefits for the island portion of the province. You might have to make some interesting choices in the design of the tunnel, which would actually lie under (or, depending on your specific choices, on top of) the ancient bed of the St. Lawrence river. It would be a delicate project, because the area is a whale’s deep and a biodiversity hub. It would be massively expensive, but so was the Chunnel.

As we move towards the implementation of the strait-crossing Maritime Link, it’s worth wondering whether we could make the entire exercise more beneficial on all sides.