This course offers an in-depth discussion of waves in fluids, with a focus on rotating and stratified fluids and applications to the ocean. Topics include dispersive and non-dispersive wave propagation, propagation in inhomogeneous media, WKB approximation and ray tracing, elements of wave-mean flow interaction theory. These principles will be applied to sound waves, surface gravity waves, internal gravity waves, and Rossby waves. Consequences for the general circulation of the ocean and opportunities for observing the ocean will serve as motivation.