A respected naval commander is on his last submarine voyage in the USS Neptune before his retirement. The craft has surfaced and is returning to port in heavy fog when it is struck by a freighter. The Neptune sinks onto a canyon ledge on the ocean's floor, and then a landslide rolls it to an angle t

A respected naval commander is on his last submarine voyage in the USS Neptune before his retirement. The craft has surfaced and is returning to port in heavy fog when it is struck by a freighter. The Neptune sinks onto a canyon ledge on the ocean's floor, and then a landslide rolls it to an angle that prevents the Navy's Deep Submergence Vehicle from rescuing it and its crew. Their only hope is Snark, a small, experimental submarine, and its unconventional commander.