Davy Jones's locker vs ocean bottom

Davy Jones's locker and ocean bottom both are nouns.

Word	Noun	Adjective	Verb	Adverb
Davy Jones's locker	Yes	No	No	No
ocean bottom	Yes	No	No	No

As nouns, Davy Jones's locker and ocean bottom are synonyms defined as:

Other synonyms of Davy Jones's locker include Davy Jones, ocean floor, sea bottom, sea floor, seabed.

Davy Jones's locker (noun)	ocean bottom (noun)
the bottom of a sea or ocean	the bottom of a sea or ocean