Amidst a storm, a boat is being piloted across the South China Sea by John Finnegan (Treat Williams). With him are his crewmen Joey "Tooch" Pantucci (Kevin J. O'Connor) and Joey's girlfriend Leila (Una Damon). Finnegan has been hired to transport a group of mercenaries, led by a man named Hanover (Wes Studi), to an undisclosed location in the middle of the ocean.
Meanwhile, the luxury cruise ship Argonautica is undertaking its maiden voyage. The ship is the brainchild of Simon Canton (Anthony Heald), designed to be the most luxurious passenger vessel ever built, catering only to society's élite. Canton and the ship's captain, Atherton (Derrick O'Connor), discover a woman named Trillian (Famke Janssen) attempting to steal from the ship's vault. They lock her in a storeroom as the brig is incomplete. Soon after, a saboteur disables the ship's navigation and communication systems. A large object is then detected on the sonar, rising from beneath and headed towards the ship. It collides with the vessel, bringing it to a violent stop and leaving it dead in the water, while the panicking passengers begin to be attacked by unseen creatures. Soon afterwards, Finnegan's boat collides with a speedboat shaken loose from the Argonautica during the commotion, causing severe damage. Finnegan's boat limps onwards to the cruiseliner, which is revealed to be the mercenaries' target; they intend to rob the ship's vault and its wealthy passengers, before sinking the vessel with torpedoes they have brought along. The majority of the group transfer over to the ship while Leila and mercenary Billy (Clint Curtis) remain on Finnegan's boat to conduct repairs. The others explore the abandoned ship, finding only blood and damaged superstructure. They also begin to hear screeches and ominous sounds on the ship. Back on Finnegan's boat, Leila is violently dragged overboard, while Billy also disappears. Finnegan and Joey go to the cruiseliner's engine room to scavenge the parts they need to repair the engines on their own vessel, under guard of T-Ray (Trevor Goddard) and Mamooli (Cliff Curtis). Both mercenaries are killed by the creatures, but Finnegan and Joey escape with the necessary parts. They run into Trillian, who has escaped from the storeroom and is unaware of what happened on the ship. They are quickly captured by the remaining mercenaries, who still intend to break into the ship's vault before leaving. Vivo (Djimon Hounsou) opens the vault, but is killed with an axe by Canton, who was hiding inside with Captain Atherton, as well as three passengers who are then machine-gunned by Mulligan (Jason Flemyng).
Canton and Atherton explain that the ship was attacked by unknown creatures that killed everyone else on board; the group soon discovers human skeletons stripped clean of flesh in the bottom of the ship. After questioning, Canton is also found to be the individual responsible for sabotage of the Argonautica; he hired the mercenaries to destroy the ship so that he could collect on the insurance, having realised that he badly misjudged the market and was left with an immensely expensive vessel that would never turn a profit. The mercenaries' payment was to be by way of the robbery they had planned, while Canton insists the passengers would've been safely evacuated in the lifeboats. The group is suddenly attacked by the creatures, revealed to be giant tentacles, one of which is shot open, revealing Billy's half-digested body. Captain Atherton is also killed, and the remaining survivors reluctantly agree to work together to escape. Canton theorizes that the tentacles are an extreme evolution of smaller deep-sea worms which strip their prey of body fluids and then eject the carcass.
The group is forced to swim through a flooded section of the ship to reach an exit; Mason (Clifton Powell) is the last in line and is attacked, and he kills himself with a grenade before he can be eaten. Once through, Mulligan goes insane and attempts to stand alone against the creatures, giving the others a chance to escape before he too is killed. It soon becomes apparent that the tentacles are herding the survivors to the bow, where they find a "feeding room" full of the carcasses of the passengers and crew. When the creatures break through the hull and flood the lower decks, the survivors become separated. Hanover tries to sacrifice Joey to save himself, but Joey escapes and Hanover is himself eaten. Canton realizes the ship is sinking, meaning he would collect the insurance money after all, and plans to abandon the others to their fate.
Finnegan and Joey make it back to Finnegan's boat, but they have lost the engine parts necessary to repair it, meaning it is useless as a means of escape. They spot an island in the distance, although it is too far away to reach on the damaged boat. They instead set the boat's autopilot to crash into the Argonautica, thereby detonating the mercenaries' torpedoes and destroying the cruiseliner and the creatures with it. Finnegan returns to the ship to find jet skis they can use to reach the island, but is forced instead to rescue Trillian from Canton, who intends to eliminate her as she is a witness to his scheme. Canton escapes moments before the tentacles smash through the deck from below, revealing them to be part of a single giant creature, which attacks Finnegan and Trillian. They barely manage to escape and return to Finnegan's boat, where they discover Joey gone amidst evidence of another attack. Finnegan sets the boat's autopilot and leaves the doomed cruiseliner on a jet ski with Trillian. Desperate to escape, Canton jumps aboard Finnegan's boat, but cannot disable the autopilot and is killed when it collides with the Argonautica, the explosion destroying the entire ship and killing the creature.
Finnegan and Trillian reach the nearby island covered with jungles where they are reunited with Joey, who survived the ordeal and paddled ashore using Finnegan's surfboard. As the three relax and admire the beauty of the island, a loud roar echoes from the forest and something huge crashes toward them through the trees. The camera pans out to reveal multiple active volcanoes within the core of the island, while an exasperated Finnegan mutters, "Now what?"
Treat Williams as John Finnegan
Famke Janssen as Trillian St. James
Anthony Heald as Simon Canton
Kevin J. O'Connor as Joey "Tooch" Pantucci
Wes Studi as Hanover
Derrick O'Connor as Captain Atherton
Jason Flemyng as Mulligan
Cliff Curtis as Mamooli
Clifton Powell as Mason
Trevor Goddard as T-Ray Jones
Djimon Hounsou as Vivo
Una Damon as Leila
Clint Curtis as Billy
Stephen Sommers began writing the script to Deep Rising, then called Tentacle, when he worked at Hollywood Pictures in the mid-1990s. Claire Forlani was originally cast as Trillian St. James, but dropped out after just three days, due to creative differences with Sommers, and Famke Janssen was subsequently cast. Janssen almost did not get the part because the producers felt she was too recognizable from GoldenEye, but they relented. Harrison Ford turned down the role of John Finnegan, which later went to Treat Williams, and the film's budget was later downsized.
Filming for Deep Rising began on June 12, 1996 and lasted until October 18 of that year. The film was originally set for release in the fall of 1997, but was delayed until the following January.
Deep Rising received mostly negative reviews. At Rotten Tomatoes, it has a "Rotten" rating of 31%, based on 29 reviews. It also made Roger Ebert's most hated films list. In his own words, "Deep Rising is essentially an Alien clone with a fresh paint job". On its opening weekend the film made $4,737,793 (42% of its total gross), ranking #8. It ended up being a box office bomb, with a total intake of a little over $11.2 million.