"Under" is a song about a couple enjoying a beautiful moment by the water. The lyrics describe how the couple admires the sunset and shares their thoughts about life, love, and the future. The chorus is about committing fully to a relationship, even if it means risking heartbreak or uncertainty. The lyrics suggest that the singer wants to be embraced so tightly by his lover that he feels completely submerged in their love. The song has an introspective and emotional tone, with the singer contemplating the complexities of relationships and the fleeting nature of happiness. The music is a mix of electronic and acoustic sounds, with atmospheric textures and a catchy chorus. Overall, "Under" is a heartfelt love song that captures the mood of a special moment between two people.