The Abyss (1989)

In James Cameron's expensive but impressive landmark science-fiction adventure film with a pacifist message similar to the one in The Day The Earth Stood Still (1951) - with four Academy Award nominations, it won the Oscar for Best Visual Effects:

• in the startling, credit-less opening title sequence, the words "THE ABYSS" emerged from the darkness, and then the camera descended down into the letter "Y" into the ocean - there appeared a view of an American, ballistic missile nuclear submarine, the U.S.S. Montana; the experimental submarine was on patrol near the Cayman Trough, a very deep water area, and experienced a momentary loss of power
• in early 1994, when the US submarine attempted to follow a fast and highly maneuverable entity (or "bogey") - possibly a provocative alien species, it unexplicably struck an undersea mountainous ridge and quickly sank into the abyss, falling into the deep Caribbean Sea waters (about 25,000 feet down); this was soon after followed by a frighteningly-realistic drowning scene, and a scene of divers surveying the drowned corpses - with facial expressions that mocked death
• with a hurricane and the Soviets approaching, the US Navy attempted a rescue and salvage operation, by requesting and demanding help from the crew of an underwater oil-drilling platform known as Deepcore - the prototype of a roving, seabed oil-drilling station; the assignment was to be reluctantly led and conducted by Deepcore's rig foreman Virgil "Bud" Brigman (Ed Harris), and his assertive, estranged wife Dr. Lindsey Brigman (Mary Elizabeth Mastrantonio), Deepcore's designer and project engineer; both would now be forced to work closely together even though there were involved in a pending divorce
• the Deepcore personnel members were also joined by US Navy SEAL commandos, headed by Lt. Hiram Coffey (Michael Biehn), who was leading the effort to untrigger the sunken submarine's cargo of 24 potent, Trident nuclear missile warheads: ("8 M.I.R.V.s per missile - that's a hundred and ninety-two warheads"); it was revealed, as a foreshadowing, that he was susceptible to pressure sickness (known as HPNS - "High Pressure Nervous Syndrome") that was known to drive individuals insane
• the film featured many computer-generated images during enigmatic encounters with the alien craft and visits with the watery, luminous abyss-dwelling aliens - known as NTIs (Non-Terrestrial Intelligences), including the revelatory emergence of a glowing purple/pink ship in front of Lindsey -- and her later description of it to "Bud": ("It... it was like a dance of light!")
• in the amazing "pseudopod" sequence, a CGI water-based tentacle or tube of water morphed into the faces of Lindsey and Bud
• Coffey was intent on destroying the NTIs, and armed a warhead retrieved from the submarine to eliminate the aliens; during Lt. Coffey's two major tense, action sequences after he became delusional and paranoid from the intense pressure, he knife-fought with Bud and engaged in a "chase" scene involving two mini-submersibles that culminated in Coffey's death when he was crushed within his submersible by the pressure, but Bud and Lindsey were stranded in their leaking mini-submersible with only one aqualung
• Lindsey made the devastating decision to let Bud use their sub's sole diving suit to swim back to the platform, towing her body behind him in the frigid water
• subsequently, Lindsey drowned (went into deep hypothermia) and Bud was called upon to frantically resuscitate her using a combination of methods: heart-shocks, pounding on her chest, screaming at her, slapping her, crying, and mouth-to-mouth CPR, until she gasped and took a breath: ("No! No, she has a strong heart! She wants to LIVE! C'mon, Linds! C'mon baby! Zap her again! Do it!... Do it!... Come on baby, come on baby!... Come on, breathe baby. Goddamn it, BREATHE! Goddamn it, you bitch, you never backed away from anything in your life! Now fight! Fight! Fight! Right now! Do it! FIGHT, GODDAMN IT! FIGHT! FIGHT! Fiiiiiiiiiiight! Fiiiiiiiiiiight! That's it, that's it, Lindsey. That's it, Linds, you can do it. That's it, Linds, come back, baby. Come on. You can do it, baby")

Near Drowning Death of Lindsey

• the resuscitation sequence was paralleled by Lindsey's speech to Bud when he decided to engage in a free-fall wearing an experimental diving suit (breathing oxygenated fluid instead of air) - a possible 'one-way' trip to descend into the 2.5 mile deep Abyssal Trench to defuse a nuclear bomb warhead; Lindsey sent heartfelt and reassuring messages to her estranged husband that were relayed to him as he descended dangerously into a deep ocean trench to disarm the nuclear warheads on the submarine: ("I know how alone you feel... alone in all that cold blackness... but I'm there in the dark with you. Oh Bud you're not alone...I'm with you. I'll always be with you, Bud, I promise that")
• after dismantling the warhead in a tense sequence (he had to guess the wire to be cut), Bud ran out of oxygen, and was encountered by beneficent, angelic-looking NTI's (Non-Terrestrial Intelligences) who rescued him; they took him to their awe-inspiring underwater city and their mothership - in a 2001-ish and/or Close Encounters-like sequence
• during his time with the NTIs, Bud was shown TV clips about the destructive nature of human beings with images of war, genocide and aggression - one of the originally deleted scene (restored in the director's cut) was the astonishing "tidal wave" sequence in which both coasts (and an unnamed Russian port and other global locations) were threatened by massive amounts of water (1,000 foot high tidal wave megatsunamis controlled by the NTIs - but then subsided (followed by a warning from the aliens to Bud and all of humanity against war-like aggression); they changed their minds due to Lindsey's compassionate message to Bud: "LOVE YOU WIFE"
• the film concluded with the rise of the alien ship to the ocean's surface, the saving of the Deepcore crew, and a reunion between Bud and Lindsey after their greeting: ("Hi, Brigman," "Hi, Mrs. Brigman")