A Ship that is Capable of Travelling in Any Direction
Nearly every nation on earth has at least one submarine service in its navy. However, not every citizen of these countries is granted the freedom to travel wherever they like. Because of the cooperation of these countries, the United States is able to sneak its submarine throughout the world without raising suspicion.
They have a significant advantage over everyone else on Earth due to the fact that they can launch attacks from quite a distance away. This gives them an opportunity to cause maximum damage. You can see that it is not an easy task, but despite this, it is an endeavour that is of the utmost significance.