James Cameron’s The Abyss was released in theaters on 9 August 1989. Exactly three months later, the Berlin Wall was demolished, putting a symbolic end to the Soviet bloc and the decades-long tensions that went along with it. It’s easy to forgot how closely these two events coincided, perhaps because Cameron’s films have always seemed directed toward the future, deploying technologies that wouldn’t take hold in the industry for years later. But The Abyss is as old to us now as Alfred Hitchcock’s North By Northwest or Billy Wilder’s Some Like It Hot was to audiences in 1989, and it is the product of a generation that grew up fearing nuclear annihilation. Expected it, even.

Yet the message of The Abyss wasn’t bandied about much at the time, in part because that aspect of the film was badly mangled for the theatrical cut (more on that later) and in part because the presumed folly of its making was taking up much of the oxygen. It’s a pattern that would repeat itself later in Cameron’s career with Titanic and Avatar: reports of cost overruns and directorial hubris, followed by a film that hit the culture like the tsunami it didn’t get to see back in 89. The Abyss wasn’t nearly as successful as the other two, granted, but it did push blockbuster art forward, anticipating the leap to digital effects that would seize Hollywood in the next decade, starting with Cameron’s own Terminator 2: Judgment Day two years later.

The production stories aren’t worth rehashing in full, though it seems likely that the behind-the-scenes discord on The Abyss would be mentioned in the same breath as Apocalypse Now or Fitzcarraldo if its making had been documented as closely or if its stars, Ed Harris and Mary Elizabeth Mastrantonio, had not refused to discuss it. Even a promotional junket couldn’t keep the toxic floodwaters from gushing into outlets such as the New York Times, which described a harrowing six-month affair where 40% of the action took place underwater, in two tanks at an abandoned nuclear power plant in South Carolina. Beyond the notorious challenges of shooting on water – which famously tamed Steven Spielberg on Jaws, a film that spends far more time on dry land – the tension between Cameron and his three lead actors was often explosive. (Cameron expressed “limited sympathy” for them on the promo tour, which happens precisely never on those things.)

Photograph: Allstar/Cinetext/20 CENTURY FOX

In broad strokes, The Abyss is Cameron’s Close Encounters of the Third Kind, a big-hearted sci-fi epic about the interchange between humanity and aliens of uncertain motivation. It also returns Cameron to the militaristic tough-talk of Aliens, only here a few navy seals, led by Michael Biehn’s duplicitous Lt Coffey, join forces with a blue-collar oil-rigging crew that has more in common with the commercial refinery towers in Ridley Scott’s original Alien. When a US submarine sinks mysteriously near the Cayman trough, the roughnecks aboard an underwater drilling platform, led by foreman “Bud” Brigman (Harris), are asked to take part in the investigation, which involves nuclear warheads. (Or to put it in Cameron-ese: “Jesus Christ, it’s World War III in a can!”) Coffey is accompanied by the rig’s designer, Dr Lindsey Brigman (Mastrantonio), introduced as “Queen Bitch of the universe” before Bud, her estranged husband, grumbles about how hurricanes should be named after women.

The visual wonders of The Abyss haven’t been blunted by time, though the CGI, at that stage of its development, looks much better in the deep, dark sea than above the surface. At 12,000-plus feet below, the alien platform looks like an arcade Atlantis, a cross between the Star Gate from 2001: A Space Odyssey and a neon paradise; in the sunlight, it’s more like a wavy slab of slick plastic. The creatures themselves, glowing and undulating like purple amoeba, now seem like a prototype for Avatar’s color scheme, but the simplest effect, of water taking shape and breaking apart, is the most arresting. A scene where a wormlike shaft of seawater mirrors Bud and Lindsey’s faces is the one genuinely Spielbergian moment in the film, and presages the liquid metal Cameron would marshal to such great effect in T2.

Between the 140-minute cut released to theaters in 1989 and the 171-minute special edition unfurled on LaserDisc in 1993, The Abyss gained in interest and reputation, if only because the longer cut substantially changed the finished product. It was Cameron, not the studio, who opted for the shorter version, which is unquestionably better paced and more focused, and without the high cheese of alien beings communicating anti-nuclear sentiments via cable news clips. Yet the thematic heart of the film is weakened in the theatrical version, which feels like a studio hack job even if Cameron was ultimately responsible. It may be tacky to write a story about underwater creatures who rise up to protest nukes – and who spares humanity from mega-tsunamis because of one man’s texts to his wife – but it was a mistake not to commit to it.

For all its mammoth ambition, both as technical marvel and political statement, the one unvarnished triumph of The Abyss is the love story. Perhaps those 70-hour weeks under Cameron’s dictatorial hand forged the right mix of exhaustion and esprit de corps between Harris and Mastrantonio, but they suggest a bond that may be messy and contentious, but deepens under duress. Bud and Lindsey watch each other drown and come back to life in the final third of the film, which would feel like emotional overkill if the two actors weren’t giving so much of themselves in willing for the other’s resurrection or if Cameron didn’t believe in this screwed-up marriage so fervently.

In the editing room, Cameron cared more about salvaging this relationship than saving the planet. When Bud gets his message from the deep and texts it back to humankind, the line “They’ve left us alone, but it bothers them to see us hurting each other” is intended to be about the horrors of war, but it is just as much a statement about romantic partners who have sabotaged their own union.

“They want us to grow up and put away childish things,” the message continues. “Of course, it’s just a suggestion.”