Stretching across the Bering Strait, it would require an underwater ... and construction is well underway for the ambitious project. Although this tunnel is significantly smaller than the Channel ...

It's not clear how cars are going to hop across the Bering Strait, but it could be via a ludicrously long bridge or perhaps through a great big tunnel under ... sees the project as essential ...

The Strait of Gibraltar tunnel project stands to link Spain and Morocco, allowing users to drive 300 metres below sea level at its lowest point for an estimated 12.8million people annually.