Tunnels are one of greatest masterpiece of architecture that the human race has ever built. It has saved a lot of time and money for transporting of materials and its use as a commutation option as well. Building tunnels on land surface are much easier as compared to the underwater tunnel. Underwater tunnel as a whole involves more labor, time and money than normal tunnels.
The oldest underwater tunnel ever built was that on river Thames also known as Thames tunnel. It is 0.44 km long and took almost a decade to build as the technology available at that time was very obsolete. It involved a lot of human labor and very few machines were available at that time for reducing the amount of work that goes into the building of such tunnels.
The longest underwater tunnel ever built is Seikan Tunnel which is located beneath Tsugaru Strait. It has the length of 53.9 km and connects Hokkaido Island to Aomori Prefecture. The underwater tunnel was built in the year 1988. it took Japan almost 3 years to build this tunnel as the technology in Japan is very much advanced as compared to other parts of the world.
Also Read: How are bridge columns built underwater?
The main advantages of underwater tunnels are that it allows ships to pass above them while still serving as a commutation option for others to use. It is very fast to commute rather than using the traditional water route. Connect two or more places which otherwise would only have been possible by air or by boats/ships.
Moreover, It provides the opportunity to see the real-time sea life also if the walls used are transparent in nature. It often comes to our mind as to when and how such underwater tunnels might have been built? The answer to this question dates back to the year 1818, when Marc Brunel, a French inventor built a device called TBM or Tunnel Boring Machine. They are also called moles.