The term Steampunk refers to a sub-genre of science fiction and fantasy that usually takes place in the Victorian era, yet includes advanced technology from the 19th century. Steampunk themes feature highly advanced machinery and imaginative inventions. Steampunk movies will either take place in a fantasy world or in a recognizable period of history.
One of the best known Steampunk movies is 20,000 Leagues Under the Sea, based on the novel written by Jules Verne. This movie features a highly advanced submarine whose technology is decades ahead of the time period. Set in the year 1868, the plot consists of sailors who are forced to cancel a voyage due to rumors circulating about a dangerous sea monster. A marine biologist and two others set out on an expedition to try to find the monster, which turns out to be a large submarine. After their ship is damaged, the three men are taken aboard the submarine, where they meet Captain Nemo. The vessel is called the Nautilus, and was built secretly by Nemo for the purpose of exiling himself from civilization, while at the same time conducting his scientific studies.
Because Nemo is afraid that the three men will betray him and reveal him to society, he tells them they have to remain on the boat and can never leave. During their voyage, the men are able to see the corals of the Red Sea and scenes from other factual historical events, as well as see the remains of the lost city of Atlantis, which is a fictional place.
This movie falls into the Steampunk category because of the highly advanced submarine, which had not been yet invented at the time. It also makes reference to actual places and historical events, as well as incorporating fictional places into the story. This movie is recognized as being of the earliest films of the Steampunk genre and as one of the best known Steampunk movies.