DeepStar Six™ is an all-the-way underwater Navy-funded sub-station with a science/janitor crew setting up a missile silo, which will later be used to blast Russia or whales right in the blow-hole.
The constantly bickering crew has fatigue syndrome, which makes the confined workspace more socially exciting. While drilling through a sea wall, a mini-sub is attacked by a prehistoric monster that looks like one of the graboid sand worms in Tremors (1990). Never mind that this movie came out before Tremors did – the worm was copied, I tell you.
The aquatic monster barely makes an appearance at this point, and doesn’t show up again until the last 30 minutes when it gets inside an air lock and goes after the crew, whose numbers fall prey to severed limbs and liquid-filled lungs.
Swear word-infused yelling, a torso bit in half here, a heart exploding there, but mostly a dry tale of underwater horror. Not to be confused with The Evil Below, The Rift (Endless Descent), Lords of the Deep, Leviathan, and The Abyss, all of which had pretty much the same plot and came out the same year as DeepStar Six (1989). Hollywood needs a new lifeguard.