natator vs skin-diver

natator and skin-diver both are nouns.

Word	Noun	Adjective	Verb	Adverb
natator	Yes	No	No	No
skin-diver	Yes	No	No	No

As nouns, skin-diver is a hyponym of natator; that is, skin-diver is a word with a more specific, narrower meaning than natator:

natator: a person who travels through the water by swimming
skin-diver: an underwater swimmer equipped with a face mask and foot fins and either a snorkel or an air cylinder

Other hyponyms of natator include floater, aquanaut, surfboarder, surfer.

natator (noun)	skin-diver (noun)
a person who travels through the water by swimming	an underwater swimmer equipped with a face mask and foot fins and either a snorkel or an air cylinder