tranquil vs serene

tranquil and serene both are adjectives.

Word	Noun	Adjective	Verb	Adverb
tranquil	No	Yes	No	No
serene	No	Yes	No	No

As adjectives, tranquil and serene are synonyms defined as:

Other synonyms of tranquil include calm, unagitated.

tranquil (adjective)	serene (adjective)
(of a body of water) free from disturbance by heavy waves	completely clear and fine
not agitated; without losing self-possession	not agitated; without losing self-possession