Sea and ocean depths contain lots of secrets. So, underwater travel dreams have always been in the hands of inventors and engineers. Jules Verne's book 20 Thousand Leagues under the Sea was the first diesel punk novel dedicated to the underwater journey. She was a motivation to designers and engineers to come up with the submarine prototypes. Deep-sea vehicle prototypes appeared in the early Middle Ages, but it was until 1620 that the first successful submarine tests happened in England. Presently, underwater vehicles are the most intricate mechanical-electronic systems that can manage several months of underwater trips and explore the deepest depths of oceans in the world.