On reflection after a recent re-watch, I've decided that The Hunt For Red October has everything I look for in a hard science fiction film.

A complete, functional universe with its own rules and jargon. This film mostly takes place in the north Atlantic Ocean, an extremely hostile environment where life, while practical and even routine, has to follow completely different rules from those that most of us are familiar with. Red October presents a relatively small window on this universe, or maybe a tour of its most interesting parts. The sensation, though, is that this is a place where these people have been carrying out difficult work for decades, work which is going to continue for decades after the film is over. The scenario is consistent and convincing. "There are other stories here, but today we show you this one."

Everything's explained, but never dumbed down. The audience has to pay attention. I'm thinking of things like the Crazy Ivan manoeuvre, the caterpillar drive's noise, or navigating "Red Route 1". These things are almost certainly new to the audience. They do get explained, reasonably articulately at that, but the film is loaded with them, and you need to keep up. And while you don't have to catch all of them, you're rewarded if you do, because none of it's wasteful. It all feeds back into the action.

Highly competent characters. It's customary in a film set in an unfamiliar environment - as much of science fiction is - to throw in a viewer surrogate character. This character can ask the questions that the audience wants to ask, and the explanation comes back to both the character and the audience simultaneously. In Red October, not so much. Certainly, it would be highly unrealistic for someone with no experience to lead the action. It would also slow the film down. Having competent characters also means that the stakes always stay real. And it's refreshing that the conflict isn't caused by mistakes, stupidity or irrationality.

Plausible technology. This is where we get into "hard" part of "hard science fiction". Barring the possible/probable/inevitable technical inaccuracies and exaggerations for the sake of the thrill, the only thing in the film which is actually impossible is the caterpillar drive. Red October takes that single conceit and uses it well, actually framing the story around it, making the artifact work to earn its place in the story. And the rest is concrete. We never pull nonsense technology out of nowhere to get out of a horrible jam. "Oh, if I crosswire the nuclear reactor to the caterpillar superconductors, we can accelerate to faster than any torpedo-- but just for a few seconds!"