In the 20th century, attempts were made to create an underground boat

Underground Boat - in draft form, and fiction in a self-propelled mechanism machine controlled located inside the crew and the ability to move underground, working his own way. During the XX century underground boat projects of varying degrees of realism developed in many countries, particularly in Germany and the USSR.

In the USSR such a device called the "Battle mole" was tested in 1964. The boat, which can reach a speed of 7 km / h and can accommodate up to five crew members have successfully passed through the mountain. However, in the second test car exploded and stayed with people underground, and soon after that project is minimized.

via factroom.ru