"sea of flags" was written in two days by mauboy, ilan kidron and stuart crichton, and was also produced by crichton. musically, it is an uptempo four-chord song with a synthpop production. its instrumentation consists of a guitar riff, a tribal drum arrangement and "synthesized" backing vocals. the introduction features backwards sounds, while the final chorus of the song incorporates ad-libs and harmonies. lyrically, "sea of flags" reflects mauboy's indigenous australian culture and the eurovision tradition of waving flags in support of the countries represented in the competition. andrew le of "renowned for sound" added that the lyrics includes lines "of a united world with colours connecting, dancing and hope." le also noted that the tribal drum arrangement in "sea of flags" was a nod to mauboy's and australia's indigenous heritage. he further noted that her vocals in the song's verses "are steady yet self-assured", but get higher and louder in the chorus. mauboy spoke about the song's development in an interview for "the sydney morning herald", saying that "i really wanted to make it quite spiritual, quite tribal, [about] where i come from – northern territory, darwin...i was feeling earthy that day, so i really wanted to make it all about my upbringing, the next generation and being a leader, someone who inspires others. there's also some ancient dreaming in there; definitely a storytelling thing."