“The Longest Wave” was inspired by Anthony Kiedis’ two year relationship with Helena Vestergaard, his model ex-girlfriend. As with several other songs on The Getaway, the lyricism outlines the inevitable end of a romance. In the song, Kiedis also alludes to the age difference between himself and Helena, describing her as being “under my skin and half my age.”

Anthony Kiedis described the writing process in a track-by-track video commentary for the song:

I went away by myself and got in touch with my feelings and kind of woke up in the middle of the night hurting over a relationship that just didn’t pan out, and sat there next to my bed with some stupid little old boom box with batteries running out and played that song over and over and found my rhythm […] And being in the state of mind that I was, the images and everything just sort of flowed.

Initially, the song’s working title was “The Philippines,” and originated from a piece of music created by guitarist Josh Klinghoffer. Speaking about this, Kiedis recalled:

He had that guitar part, which is just super gorgeous and original sounding and I fell in love with it quite early.