TED Ed (Animation) - How the world's longest underwater tunnel was built, 30032020

Discover how the English Channel Tunnel was built and the engineering challenges of building a 200 kilometre long tunnel underwater. Flanked by two powerful nations, the English Channel has long been one of the world’s most important maritime passages. Yet for most of its history, crossing was a dangerous prospect. Engineers proposed numerous plans for spanning the gap, including a design for an underwater passage more than twice the length of any existing tunnel.