Charlton Heston portrays the Captain of the "USS Neptune," a nuclear submarine concluding its final assignment and headed back to harbor. While operating on the surface, the vessel strikes a Norwegian boat with malfunctioning radar equipment, plunging them into the depths of the Atlantic where they become trapped on an unstable ledge vulnerable to landslides. A desperate effort to save the sailors begins, bringing Stacy Keach ("Capt. Bennett") aboard to direct the rescue operation, assisted by "Capt. Gates" (David Carradine), who arrives with his innovative “Snark” DSRV. Predictably, conflicts arise among the personnel, and moments of fear and outbursts are employed to build narrative tension and excitement – these techniques prove effective within the submarine’s crew but less so amongst those involved in the surface rescue where the performances feel somewhat exaggerated. Setting it apart from many similar disaster films, the movie features impressive technology that contributes to a sense of believability.

Source on TMDB