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.
In October 1991, the commercial fishing boat Andrea Gail returns to port in Gloucester, Massachusetts, with a poor catch. Desperate for money, Captain Billy Tyne (Clooney), convinces the Andrea Gail crew to join him for one more late season fishing expedition. The crew heads out past their usual fishing grounds in the Grand Banks, leaving a developing thunderstorm behind them. Initially unsuccessful, they head to the Flemish Cap, where their luck improves. At the height of their fishing the ice machine breaks; the only way to sell their catch before it spoils is to hurry back to shore. After debating whether to sail through the building storm or to wait it out, the crew decides to risk the storm. However, between the Andrea Gail and Gloucester is a confluence of two powerful weather fronts and a hurricane, which the Andrea Gail crew underestimates.
On the MS Poseidon, a luxury ocean liner, former New York City Mayor and fireman, Robert Ramsey (Kurt Russell), is traveling with his daughter Jennifer (Emmy Rossum) and her boyfriend Christian (Mike Vogel), soon to be engaged. Also on board is professional gambler Dylan Johns (Josh Lucas), architect Richard Nelson (Richard Dreyfuss), Maggie James (Jacinda Barrett) and her son, Conor (Jimmy Bennett), stowaway Elena (Mía Maestro), and waiter Valentin (Freddy Rodriguez).
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.
In 1820, the whaling ship Essex is crewed by the Captain George Pollard, Jr., first officer Owen Chase, second officer Matthew Joy, and cabin boy Thomas Nickerson. During their voyage, the ship is sunk when it is rammed and split in half by a very large and enraged bull sperm whale, ultimately leaving its crew shipwrecked at sea for 90 days and more than a thousand miles from land. After the attack, the crew sails for South America and is forced to resort to cannibalism.
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 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 the Victorian period, two young cousins, Richard and Emmeline Lestrange, and a galley cook, Paddy Button (Leo McKern), survive a shipwreck in the South Pacific and reach a lush tropical island. Paddy cares for the small children and forbids them by "law" from going to the other side of the island, as he found evidence of remains of bloody human sacrifices. He also warns them against eating a scarlet berry which is apparently deadly.
Daniel Kintner (Daniel Travis) and Susan Watkins (Blanchard Ryan) are a couple frustrated that their hard-working lives do not allow them to spend much time together. They decide to head out on a scuba-diving vacation to help improve their relationship. On their second day, they join a group scuba dive. A head count is taken, and the passenger total is recorded as 20. Daniel and Susan decide to separate briefly from the group while underwater. Half an hour later, the group returns to the boat. Going by the tally sheet, the total comes to 20, though in reality, it is 18. Daniel and Susan are still underwater and have not yet realized that the others have returned. The boat leaves the site. Not long after, Daniel and Susan return to the surface and look for it. They believe the group will return to recover them in reasonable time.
The rescue mission took place in 1952 off the Cape Cod coast after two oil tankers, SS Fort Mercer and SS Pendleton, were destroyed by treacherous winter winds and waves. The crew of motor life boat CG 36500 and the crew of a surfboat from the USCGC Yakutat heroically rescued nearly all the tankers' crewmen.
Eleven-year-old Kevin has a vivid imagination and is fascinated by history, particularly Ancient Greece; his parents ignore his activities, having become more obsessed with buying the latest household gadgets to keep up with their neighbours. One night, as Kevin is sleeping, an armoured knight on a horse bursts out of his wardrobe. Kevin is scared and hides as the knight rides off into a forest setting where once his bedroom wall was; when Kevin looks back out, the room is back to normal and he finds one of his photos on the wall similar to the forest he saw. The next night he prepares a satchel with supplies and a Polaroid camera, but is surprised when six dwarves spill out of the wardrobe. Kevin quickly learns the group has stolen a large, worn map, and are looking for an exit from Kevin's room before they are discovered. They find that Kevin's bedroom wall can be pushed, revealing a long hallway. Kevin is hesitant to join until the visage of a menacing head – the Supreme Being – appears behind them, demanding the return of the map. Kevin and the dwarves fall into an empty void at the end of the hallway.