An adventure that takes place either under or on the sea. There were several very popular sea-based adventures in the '50s and '60s, two of the more memorable being 20,000 Leagues Under the Sea, which takes place on a submarine, and John Huston's Moby Dick. Beginning with James Cameron's effects-laden underwater epic The Abyss, there was a notable resurgence of this subgenre in the '90s. The large expanses of water and the mystery of the deep are two very different stages on which to play out these various adventures, but they provide a similar undercurrent. On, or under water, man is confronted with himself in a place with no civilization or stable piece of land to take a stand on. He is stranded in an endless mystery, and so his actions are amplified in their importance. One mistake for the underwater crew of The Abyss or Sphere and they'll be crushed under the pressure of the very substance they live in. Above water, survivors like Kevin Costner (in Waterworld) are trapped in a precarious solitude, carefully preserving everything essential, or dying of exposure.