Gray Lady Down (1978)

Charlton Heston is the Captain of the "USS Neptune", a nuclear submarine returning to port after his final mission in command. Whilst running on the surface they collide with a Norwegian boat with faulty radar and sink deep down into the Atlantic and end up perched precariously on a ledge prone to rockslides. It's now a race against time to rescue the seamen and Stacy Keach ("Capt. Bennett") is drafted in to lead the rescue with the help of "Capt. Gates" (David Carradine) who brings his revolutionary "Snark" DSRV to the scene of the accident. As usual, there are personality clashes a plenty; panic scenarios and temper tantrums as tools to try and develop story tension and suspense - they work well enough with the crew on the sub; much less so with the crew on the surface where the acting is far more of the willy-waving variety. Unlike many of these disaster movies, it's got good gadgets and they help keep it quite realistic.