Despite the first hour always being just enough watchable to keep the viewer wanting more, Leviathan doesn't properly tighten the screws of its Alien-esque horror/action until that mark, making it tepid at best. Once the creatures show up, the creature f/x is as realistic in its design as it's silly in its terror/suspense setups, making Leviathan a good time waster, if still below average.
Decompression and deep sea operations mirror it to "DeepStar Six" from the same year, but the use of claustrophobia as well as the design of body horror escapades brings it closer to "Alien" and "The Thing". It's a shame that it begins to drag at the end once it looses its clever way to build a tension in a favor of unimaginative action and not so much breathtaking monster designs.
A trashy mix up of "Alien" and "The Thing," only set deep, deep underwater a la "The Abyss." Peter Weller delivers an understated performance that conflicts with the rest of a script that has him delivering cheesy one-liners like "Say ahhh, motherfuckah!" and punching a woman in the face. Despite assured direction from Cosmatos, the filmmakers simply did not have the money to pull off a convincible movie monster.