Davy Jones’s Locker first appears in print in a 1726 voyage narrative attributed to Daniel Defoe, likely drawn from real mariners’ speech, where a pirate threatens to toss his captives into it. There it is only a euphemism for drowning and the ocean floor. By 1751 a satirical novel had given the idea a body: a fiend with saucer eyes, three rows of sharp teeth, horns, a tail, and blue smoke pouring from his nostrils, who perched in the rigging before hurricanes to mock doomed crews. Giving the indifferent sea a face acted as a psychological lightning rod, since a demon can be cursed and a random wave cannot. The name itself is never explained, and theories pull in the prophet Jonah, whose name may have drifted into Jones, and Saint David, the patron saint of Wales, whom Welsh sailors invoked in storms.

Folklore adds the West Indian duppy, a malevolent ghost, suggesting that multilingual crews blended Caribbean spirits, Welsh prayers, and Jonah into one nautical nightmare. More mundane theories point to a minor pirate named Davy Jones in the Indian Ocean in the 1630s, a clumsy, short-sighted sailor called Duffer Jones who kept falling overboard, and an alehouse keeper who locked drunk patrons in his cellar and sold them to ship captains short of men. As navigation improved, the monster lost his teeth. He became King Neptune’s first assistant in rowdy equator crossing ceremonies where shellbacks hazed polywogs, and then a stage and screen character.

• A London West End pantomime featured Davy Jones by 1812.
• In the 1930s he turned up in animated cartoons as a goofy skeleton in a pirate hat.
• A 1960s sitcom about a rock band had a real pop star named Davy Jones, spawning decades of puns.
• In SpongeBob SquarePants the locker is a literal gym locker full of souls and smelly socks.
• In a 2022 UK High Court libel trial, a judge used the idiom to describe a phone dropped into the North Sea.