Produced and directed by the man who created the Friday the 13th and House movies, this is uproarious 'B' schlock with more plot contrivances to the fathom than any sub-saga since the heady days of Gerry Anderson's Stingray.
Deepstar Six is a government missile installation project on the seabed, and it gets heavily terrorised when submarine blasting frees a prehistoric monster from a cavern. The crew of the undersea base spend their time quoting Emerson, exchanging hilarious dialogue ("Have you ever heard of photomigration?" "What do you say if it's a boy we name it after the captain?"), having sex in the shower, bickering, making stupid mistakes, panicking and getting gorily killed. The monster causes surprisingly few of the deaths, which tend to involve defective hatches chopping people in half, and bloody decompression.
In theory, it's impossible to fail with this premise but Deepstar Six nearly manages it through its sustained and almost heroic stupidity. Cunningham pulls every obvious trick in the book, and even those who haven't thought about physics since they were 13 wilt spot the mistakes in elementary science. Deepstar Six takes 99 minutes to deal with a situation Troy Tempest could have wrapped up in half an hour. Glub glub glub.