Leviathan (1989)

Somewhere in the Atlantic, a deep-sea mining operation is digging for silver.  Stephen Beck (Peter Weller) is a geologist and supervisor of the operation.  He has 6 miners and Dr. Thompson (Richard Crenna) in the facility, called "the Shack."  The rotation is 90 days, and the crew is on day 87.  They are eager to get back to the surface, especially Buzz "Sixpack" Parrish (Daniel Stern) who is clearly going stir crazy.  The following day, while looking for another vein to mine, Sixpack fell of a ledge and lost contact.  Elizabeth "Willie" Williams (Amanda Pays) went looking for him.  She only had 20 minutes of air remaining when she stumbled upon a sunken Russian ship, the Leviathan.  There she found Sixpack, who claims to be rich.  The pair return to the shack, where they open the safe that Sixpack recovered.  It is mostly junk and all in Russian.  Dr. Thompson knows Russian and doesn't like the look of this.  It's a lot of death certificates for the crew.  Checking records for the Leviathan, they can find nothing about such a ship sinking.  Mysterious.  Soon, Sixpack becomes sick.  Then Briget Bowman (Lisa Eilbacher) starts feeling ill.  Dr. Thompson can find no explanation for the symptoms.  Asking the computer to guess, it suggests genetic mutation.  What were the Russians doing on the Leviathan?

This is Alien (1979) based underwater.  The creature quickly evolves and proves bright enough to tinker with the shack's systems, trying to lure more victims out of safe areas.  It is not long before the shack is at threat of implosion as the delicate systems start to fail.  Can the miners be rescued before the genetic mutant absorbs them into its expanding mass?

Like in many horror films, the characters are far too eager to wander off alone, often wearing headphones.  As in most zombie films, a bite or scratch transmits infection.  There are clear indications that Beck and Willie might be headed for a relationship, but that is really on a backburner through the movie.  The monster, which is proposed to have the knowledge of those it absorbs, proves rather stupid.  Given that it could just swim around the sea and get bigger or spawn, it instead fixates on the crew of the shack.  Based on how it was able to respawn from a hacked off limb, the movie clearly could have a had a sequel.

One of half a dozen deep sea epics of the time - The Abyss (1989) being the most successful, this is mediocre.  Run of the mill action, cliched scares, bland characters, and weak plot, the movie is mediocre at best.  Skip.