marine archaeology vs underwater archaeology

marine archaeology and underwater archaeology both are nouns.

Word	Noun	Adjective	Verb	Adverb
marine archaeology	Yes	No	No	No
underwater archaeology	Yes	No	No	No

As nouns, marine archaeology and underwater archaeology are synonyms defined as:

marine archaeology and underwater archaeology: the archeology of underwater sites

Other synonyms of marine archaeology include marine archeology, underwater archeology.

marine archaeology (noun)	underwater archaeology (noun)
the archeology of underwater sites	the archeology of underwater sites