Submarine movies for me are basically all horror movies. Compartments are always going to flood. Someone is always going to drown. Someone is always going to have to make the terrible decision to let someone else drown. Someone is going to have to watch someone else drown through a small porthole. Someone will often be electrocuted. Someone will occasionally be crushed by explosive compression. In some rare cases, someone’s head and/or body will explode from explosive decompression.
While submarines are similar and often used as a substitution for spaceships in adventure stories, they come saddled with a key difference: we know how water works. We’ve all choked on a drink. We’ve all gotten water up our noses. Most of us know how to swim, or not, and have inhaled water instead of air while submerged. We’ve had leg cramps and found ourselves unable to swim those few inches back to the sky. We’ve been knocked down by waves and lost our sense of up or down. Some of us have been caught in riptides. Some of us have even drowned and been revived.
For most of us space is a fantasy, and all of the ways that things can go wrong in space we think of abstractly. But with submarines, we know very personally and viscerally what the consequences of the worst case scenarios are. Water is mean in so many ways that we can only imagine space to be.