In 1996, treasure hunter Brock Lovett and his team aboard the research vessel Akademik Mstislav Keldysh search the wreck of RMS Titanic for a necklace with a rare diamond, the Heart of the Ocean. They recover a safe containing a drawing of a young woman wearing only the necklace dated April 14, 1912, the day the ship struck the iceberg. Rose Dawson Calvert, the woman in the drawing, is brought aboard Keldysh and tells Lovett of her experiences aboard Titanic.
The Titanic was the largest vessel afloat, and was widely believed to be unsinkable. Her passengers included the cream of American and British society. The story of her sinking is told from the point of view of her passengers and crew, principally Second Officer Charles Lightoller (Kenneth More).
In Canada, novelist Yann Martel meets Pi Patel, an Indian immigrant with some knowledge from Pi's late father's friend, known to Pi as "Mamaji", for a good book. Pi tells Yann his life story.
Several British and U.S. civilians, service members and merchant marines are stuck in a lifeboat in the North Atlantic after their ship and a U-boat sink each other in combat. Willi (Walter Slezak), a German survivor, is pulled aboard and denies being the U-boat's captain. During an animated debate, Kovac (John Hodiak) demands the German be thrown out to drown. However, the others object, with Stanley (Hume Cronyn), wealthy industrialist Rittenhouse (Henry Hull) and columnist Connie Porter (Tallulah Bankhead), who speaks German, succeeding in arguing that he be allowed to stay. Porter, initially alone in the boat, had managed to bring her luggage with her, and her primary concern at first is a run in her stocking. She is thrilled at having filmed the battle between the two vessels, but her movie camera is the first in a series of her possessions to be lost overboard in a succession of incidents.
In 1988 a US ballistic missile submarine, the USS Montana, sinks near the edge of the Cayman Trough after an accidental encounter with an unidentified submerged object. As Soviet ships and submarines head toward the area in an attempt to salvage the sub, and with a hurricane moving in, the Americans decide that the quickest way to mount a rescue is to insert a SEAL team onto the Deep Core, a privately owned, experimental underwater oil drilling platform, located 1,700 feet (518 meters) below sea level, which will serve as their base of operations. The designer of the platform, Dr. Lindsey Brigman, insists on accompanying the SEAL team, even though her estranged husband, Virgil "Bud" Brigman, is currently serving as the platform's foreman.
The luxury liner SS Crescent Star sinks in seven minutes after striking a rogue mine in the middle of the Atlantic Ocean, taking with her nearly all of the 1156 people on board. Twenty-seven of the survivors converge on a single lifeboat designed to accommodate only nine. The dying captain passes command to executive officer Alec Holmes (Tyrone Power). Holmes then learns from "Sparks" Clary (John Stratton), the ship's radio operator, that both transmitters were destroyed before a call for help could be sent. Holmes decides to try to reach the nearest land, Africa, 1500 miles away.
In post-Soviet Russia, civil war erupts as a result of armed conflict in Chechnya. Military units, loyal to Russian ultra-nationalist Vladimir Radchenko, have taken control of a nuclear missile installation and are threatening nuclear war if either the American or Russian governments attempt to confront him.
The SS Poseidon, an ocean liner slated for retirement and scrapping, makes her way across the Atlantic Ocean and the Mediterranean Sea from New York City to Athens. Despite protests from Captain Harrison, who fears for the ship's safety, the representative of her new owners, Mr. Linarcos, insists that she make full speed towards her destination to save money, preventing her from taking on additional ballast.
In 1932, a luxury yacht is sailing through a channel off the western coast of South America. The captain is worried about the channel lights not matching the charts, but is quickly dissuaded from changing course by the wealthy passengers for the sake of time, including famous big game hunter and author Bob Rainsford (Joel McCrea). It is a calm evening, with the cheerful passengers relaxing over drinks and a game of cards. Bob and his companions are debating about whether hunting is at all sporting for the animal being hunted after a friend asks if he would exchange places with a tiger he had recently hunted in Africa. Bob replies that there are two kinds of people in the world: those who hunt and those who are hunted.
A family on their way to New Guinea is chased by pirates into a storm. The captain and crew abandon the ship leaving the family shipwrecked off an uninhabited island. Father (John Mills) and his two eldest sons Fritz and Ernst (Tommy Kirk and James MacArthur) salvage as much as they can from the wreck including livestock, tools, and even an organ. As they gather what can be removed from the ship, the pirates return and begin shooting at the ship. Fritz and Ernst begin readying the ship's cannon, but they only have one shot. Suddenly, the pirates turn around; Father has put up a flag indicating the ship is under quarantine and that there is Black Death aboard. The three men construct a tree house home on the island while the youngest boy Francis (Kevin Corcoran) investigates the wildlife and starts an impressive collection of animals including a young elephant, a capuchin monkey and two Great Danes rescued from the ship which they name Duke and Turk. Mother (Dorothy McGuire) prays to be rescued. The boys, particularly Ernst, also build inventions to provide modern amenities to the family such as drawing water and preserving food.
In 1905 William Crichton (Kenneth More) is the efficient butler in the London household of the Earl of Loam (Cecil Parker) and his family. Crichton knows his place in the highly class-conscious English society. The Earl insists that all men are equal, and to prove it, he orders his daughters to treat the staff as guests during an uncomfortable afternoon tea. Lady Brocklehurst (Martita Hunt) arrives and strongly disapproves of the arrangement, as does Crichton.
At the last minute, a wealthy American expatriate in Europe, Richard Sturges (Clifton Webb), buys a steerage-class ticket for the maiden voyage of the RMS Titanic from a Basque immigrant. Once aboard he seeks out his runaway wife, Julia (Barbara Stanwyck). He discovers she is trying to take their two unsuspecting children, 18-year-old Annette (Audrey Dalton) and ten-year-old Norman (Harper Carter), to her hometown of Mackinac, Michigan, to raise as down-to-earth Americans rather than rootless elitists like Richard himself.
Dans le golfe de La Spezia, un sous-marin de grande croisière, le A 103, entre en collision avec un navire de ravitaillement et s'immobilise à 80 mètres de profondeur. De délicates tentatives de sauvetage du bateau et de l'équipage vont s'organiser...
Une jeune femme, Miss Dorothy Gibson, relate à ses parents et à son fiancé, un marin, son aventure à bord du Titanic lors de son naufrage. Le naufrage est représenté au travers de flashbacks, de façon très romancée. Finalement, son père accepte son mariage.