hydromancy vs divination

hydromancy and divination both are nouns.

Word	Noun	Adjective	Verb	Adverb
hydromancy	Yes	No	No	No
divination	Yes	No	No	No

As nouns, divination is a hypernym of hydromancy; that is, divination is a word with a broader meaning than hydromancy:

hydromancy: divination by water (as by patterns seen in the ebb and flow of the tides)
divination: the art or gift of prophecy (or the pretense of prophecy) by supernatural means

Other hypernyms of hydromancy include foretelling, fortune telling, soothsaying.

hydromancy (noun)	divination (noun)
divination by water (as by patterns seen in the ebb and flow of the tides)	the art or gift of prophecy (or the pretense of prophecy) by supernatural means
	a prediction uttered under divine inspiration
	successful conjecture by unusual insight or good luck