In 1914 Vienna, Elsa Elsbergen volunteers for nursing, but her lies hiding her sordid past are discovered and she is turned down. However, Captain Muller believes her patriotism and background are perfect for the Austrian Department of Intelligence. His superior, Major Schmidt, wants her to become very friendly with Captain Otto von Lichstein, who is known to be spying for the enemy. Elsa is disappointed at the use that Schmidt wants to make of her, but accepts the assignment. At a party, she catches von Lichstein's eye and agrees to meet him the next night.
On a volcanic island near the kingdom of Hetvia rules Count Dakkar, a benevolent leader and scientist who has eliminated class distinction among the island's inhabitants. Dakkar, his daughter Sonia and her fiance, engineer Nicolai Roget have designed a submarine which Roget pilots on its initial voyage just before the island is overrun by Baron Falon, despotic ruler of Hetvia. Falon sets out after Roget in a second submarine and the two craft, diving to the ocean's floor, discover a strange land populated by dragons, giant squid and an eerie undiscovered humanoid race.
Two sailor buddies have their friendship torn apart after the woman they both are in love with chooses one over the other. Their relationship gets re-evaluated when one of them becomes trapped in a submarine and the other gets sent on the rescue mission.
As a young boy growing up in a Spanish family with a long and very distinguished maritime tradition, Ulysses Ferragut is regaled with tales of the sea by his retired uncle, the "Triton" (Apollon), and is particularly fascinated by his claim to have once seen the sea goddess Amphitrite. Though his lawyer father, Don Esteban, wants him to follow in his footsteps, Ulysses becomes a sailor.
The plot revolved around the recent incident involving the German commander Baron von Luxburg who sank an Argentine ship intending to frame the Entente for the act. Reports from survivors helped everyone to realize what had truly happened.
Kaiser Wilhelm II of Hohenzollern (Rupert Julian) is a vain and arrogant tyrant eager for conquest. When Belgium is invaded by the German army during World War I, Marcas, the blacksmith (Elmo Lincoln), although wounded, is able to save his daughter from the clutches of a German soldier. Soon after this, the RMS Lusitania is sunk by Captain von Neigle (Nigel De Brulier), who ultimately is driven mad with remorse. After the United States declares war, the Allied generals turn the Kaiser over to Albert I of Belgium. Incarcerated, the Kaiser faces his jailer, Marcas the blacksmith.
A strange giant "sea creature" has been rampaging the seas. The American naval ship Abraham Lincoln is sent to investigate, but is rammed by "the creature" which turns out to be The Nautilus, the fantastic submarine of the enigmatic Captain Nemo, and "Rudderless, the 'Abraham Lincoln' drifts on". Then, in "A strange rescue" he guides the sub to surface under those pitched overboard and his crew take them, including Professor Aronnax, and his daughter (who are French) below through a hatch in the surface of the deck. After they pledge not to escape, Nemo shows them the wonders of the underwater world, and even takes them hunting on the sea floor.
The film opens with the outbreak of a war in the previously peaceful kingdom of Wredpryd. Count Ferdinand is the inventor of a new submarine who is assigned to command the new ship in battle. The King of Wredpryd orders the Count to sink the "ProPatria" ("for my country"), a civilian ship that is believed to be carrying munitions as well as civilian passengers. In his mind's eye, the Count sees a vision of what would happen if he sent a torpedo crashing into the liner, and he recoils. He refuses to follow his orders, saying he is "obeying orders -- from a Higher Power." Realizing his crew will carry out the orders, the Count fights with the crew and blows up his submarine, sending it to the bottom of the sea.
Yves, a fisherman, comes home after a tiring day of fishing and soon falls asleep. In his dream, he is visited by the Fairy of the Ocean, who leads him to a submarine. Yves is made Lieutenant-in-Command and sets off on a submarine voyage.