In Captain Nemo, Jules Verne created one of the most fascinating characters in literature. One of the reasons Captain Nemo has fascinated generations of readers is that he is fully sovereign over himself and his crew. In this way, he represents an ultimate freedom that most people cannot have—the freedom to completely decide one’s own destiny.
The Nautilus is Captain Nemo’s domain, and as he is sovereign, the vessel itself is akin to a sovereign nation. It neither sails under the flag of nor recognizes the law of any nation. It has its own laws and tradition, and its own means of defending itself. Further, the crew are loyal to the ship and its captain above any nation, all of them, like Nemo, having chosen to live apart from the nations of the world.
Finally, it is worth noting that the Nautilus rarely ventures into the waters of other nations, even for supplies. It mainly keeps to international waters, where its captain and crew do not have to submit to the laws of any nation. Further, the crew of the Nautilus are able to derive most of their subsistence from the ocean, making them and the ship beholden to no nation for support, other than through trade.