The Longest Underwater Tunnel in the World — The Secret of the English Channel

How do you build a massive tunnel under the sea without letting millions of tons of water flood it? The Channel Tunnel is one of the most incredible engineering projects ever built. Stretching for about 50 kilometers beneath the English Channel, it connects England and France through a complex system of tunnels deep below the seabed. But how did engineers actually dig through the ground beneath the ocean? How did they prevent water from breaking through? And how was it possible to keep such a huge tunnel safe and dry? In this video, we reveal how the Channel Tunnel was built, the enormous tunnel boring machines used during construction, and the engineering secrets that made this seemingly impossible project possible.