The Abyss/Nightmare Fuel

While the entire movie has it's fair share of majestic moments, due to the nature of the film's location it also has it's fair share of scary moments.
 * The Opening scene, with the sinking of the USS Montana. It's filmed in a way that whether or not the NTI's are responsible or not for it's damage, that the way it gets damaged and the deaths that followed, could have happened to any submarine Military or otherwise.
 * When the Deep Core crew assists the Navy Seals in investigating the wrecked USS Montana, they stumble upon the aftermath. The ship itself looks like it's been chewed up and spat out by the elements. Everything from broken parts, to the corpses of crew members are floating around.
 * drowning in the damaged submersible (while her husband has to watch, no less). The water's rising and she's clearly terrified, trying to breathe right up until the submersible has completely flooded.