The story follows a civilian oil rig crew on the experimental platform Deep Core . Following the mysterious sinking of a U.S. nuclear submarine near the Cayman Trough, the Navy commandeers the rig to search for survivors and recover nuclear warheads before Soviet forces arrive. As a massive hurricane cuts them off from the surface, the crew encounters —bioluminescent beings living in the deep—while their lead Navy SEAL begins to suffer from high-pressure nervous syndrome. Special Edition vs. Theatrical Cut

The Special Edition (running 171 minutes) is widely considered the definitive version by critics, as it restores James Cameron's original vision for the ending.

: In the most significant addition, the NTIs use their control over water to create massive megatsunamis—thousands of feet high—threatening every coastline in the world. They show Bud (Ed Harris) a montage of human atrocities throughout history as a warning to "grow up".

: The extended cut includes numerous news reports detailing a mounting geopolitical crisis between the U.S. and the Soviet Union, placing the underwater events against the backdrop of an impending World War III.