The Thirty-Fathom Grave

"The Thirty Fathom Grave" is episode 104 of the American television anthology series The Twilight Zone.

In this naval-themed episode, the crew of a Navy destroyer hear a mysterious rhythmic noise coming from a sunken submarine.

You may or may not read the results in a naval report, because Captain Beecham and his crew have just set a course that will lead this ship and everyone on it into the Twilight Zone.In April 1963, a U.S. Navy destroyer is on a routine patrol off Guadalcanal when sonar picks up a sound beneath the waves; the crew believe that it sounds like something banging on metal.

They discover a submarine on the ocean floor, but inquiries to naval command reveal no recent sinkings in the area.

A joking suggestion from some of the crew that the sub may be haunted sends an anxious and bewildered Chief Boatswain's Mate Bell, who has been feeling unwell for a couple of days, into a frenzy of bizarre behavior, including fainting spells.

Inside the control room, he found the periscope shears cut in half, with one section swinging back and forth.

When Beecham asks him to confirm that this was the clanging noise they had heard, McClure agrees, but adds that he also saw the remains of eight dead sailors; one was holding a hammer in his hand.

1.^ The only submarine numbered 714 to ever serve with the USN was the USS Norfolk (SSN-714), which wouldn't be made for 13 years after this episode.