The Collaborative International Dictionary of English v.0.48:

Davy Jones \Da"vy Jones"\
   The spirit of the sea; sea devil; -- a term used by sailors.
   [1913 Webster]

         This same Davy Jones, according to the mythology of
         sailors, is the fiend that presides over all the evil
         spirits of the deep, and is seen in various shapes
         warning the devoted wretch of death and woe.
                                                  --Smollett.
   [1913 Webster]

   Davy Jones's Locker, the ocean, or bottom of the ocean.

   Gone to Davy Jones's Locker, dead, and buried in the sea;
      thrown overboard.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Davy Jones
    n 1: the bottom of a sea or ocean [syn: ocean floor, sea
         floor, ocean bottom, seabed, sea bottom, Davy
         Jones's locker, Davy Jones]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "Davy Jones":
   Davy, Dylan, Neptune, Nereid, Nereus, Oceanid, Oceanus, Poseidon,
   Thetis, Triton, Varuna, fresh-water nymph, kelpie, limniad,
   man fish, mermaid, merman, naiad, nix, nixie, ocean nymph,
   sea devil, sea god, sea nymph, sea-maid, sea-maiden, seaman, siren,
   undine, water god, water spirit, water sprite