seabed vs Davy Jones's locker

seabed and Davy Jones's locker both are nouns.

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

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

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

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