Davy Jones's Locker Meaning

Example : 1774: Nicholas Cresswell, The Journal of Nicholas Cresswell, 1774-7 - "Damn my eyes," says he, "they are gone to Davy Jones's locker."  NOTE: Partridge erroneously refers to this as from the journal of Richard rather than Nicholas Cresswell.1781 August, Isaac Kimber, Edward Kimber, “The Summer Theatre”, The London Magazine, or, Gentleman's Monthly Intelligencer, volume 50, page 360:  ... are discovered singing a melancholy duet, bewailing the loss of an honest tar, whom they suppose (to use the burthen of the song) "is in Davy Jones's locker."