A tunnel is typically an underground passageway, built in an effort to address the growing needs of roads, highways and bridges to handle a large volume of traffic. The exact definition of a tunnel has been twitched many times in the past. Irrespective of that, tunnels are the results accomplished by a magnificent feat of engineering, with boring giant holes in mountains, or laying several feet of pathway under the ocean. Let us have a look at the world’s strangest tunnels-