On January 1994, the Ohio-class Submarine USS Montana has an encounter with an unidentified submerged object and sinks close to the Cayman Trough. A hurricane is coming, the Russians are coming for salvage, and the U.S. Military sends a SEAL team to Deep Core, an experimental underwater drilling platform to use it as a base. The platform’s designer Lindsey Brigman (Mary Elizabeth Mastrantonio) comes along despite the fact that her ex-estranged husband Bud is the foreman on the platform.

A power cut in the submersibles leads to Lindsey seeing a strange light that she thinks is a non-terrestrial intelligence. The SEAL team leader, Lieutenant Coffey (Michael Biehn) takes one of the mini subs to recover a Trident missile warhead from the Montana. The hurricane hits above and the team is unable to disconnect from its surface support ship. The cable crane is torn off and falls into the trench, dragging the Deep Core closer to the edge. The rig is partly flooded, killing seven of the crew and damaging the power systems.

As they wait out the storm, a sentient tentacle of water explores the rig until Coffey cuts it in half by closing a hatch on it. Coffey is paranoid from high pressure nervous syndrome and is found arming the warhead to attack the aliens. Coffey escapes in a sub and is pursued by Bud and Lindsey in another sub. Coffey launches the missile into the trench but his sub falls over the edge and implodes, crushing him.

With only one functioning diving suit, Lindsey enters deep hypothermia while her husband swims back to the platform with her body. CPR eventually revives her. To disarm the warhead two miles below, Bud uses an experimental diving suit with a liquid breathing apparatus that should help him survive the crushing pressure. As Lindsey talks to him, he dives and reaches the warhead. He knows he cannot come back, but an alien approaches him and guides him to an alien city in the depths. They create a pocket of air for him. In the Deep Core, the crew see a message from him. The alien base rises to the surface, carrying the Deep Core with it. In one extended version, there is more anti-war propaganda, and the aliens threaten the world with tsunamis, but desist.

“In the Abyss” was an 1897 short story by H.G. Wells. Director James Cameron attended a lecture in high school, in which Duke University’s Johannes A. Kyista told of breathing oxygen from liquid in his lungs. Cameron and Gale Anne Hurd wrote the script for Abyss. Cameron and Hurd married before the movie, separated during pre-production, and divorced during principal photography. Much of the technology used to make the film had to be invented by the team as they went along.

Most of the story was filmed underwater and it was a horrendous shoot. Several of the stars had emotional breakdowns, including Harris and Mastrantonio. The big tank sprung a 150,000-gallon leak, there was a lightning storm, and the set was invaded by goats. Because they spent so much time in the chlorinated water, the divers’ skin burned, and their hair turned white. They had to relieve themselves in their wetsuits. People trashed their dressing rooms. Afterward, both Ed Harris and Mary Elizabeth Mastrantonio both disowned the film and never mentioned it again. It took Industrial Light and Magic six months to create 75 seconds of the water tentacle.

Of course, it went massively over budget, but it made a ton of money showing SF fans things they had never seen before. Reviewers said the gorgeous special effects could have overshadowed the production, but the movie was a gripping, claustrophobic thriller. But the alien city rising from the deeps kind of lost its magical quality in the process and it was a bit of a letdown. It was nominated for four Oscars and won for special effects. The soundtrack was by Alan Silvestri. It appears that, unlike most films, it was actually improved by the director’s tinkering afterwards.

The rats used were actually breathing liquid, but the camera cut to the faces of the onlookers to avoid filming the rats defecating in terror. One of the rats had a heart attack. Cameron revived it, kept it as a pet and it died of old age. Ed Harris punched James Cameron in the face, making many actors jealous. The actors, who did most of their own stunts called the film “Life’s Abyss and Then you Dive.” Cameron himself nearly drowned. His brother Mike Cameron played a corpse with a crab coming out of his mouth, take after take, while he held his breath.