Naufrago comes from the verb naufragar, meaning "to shipwreck" or "to be shipwrecked." It's a dramatic and evocative word that paints a vivid picture of being lost at sea.
In this song, the singer uses naufrago metaphorically to express being completely overwhelmed and lost in a "sea of abandonment" (mar de tu abandono). It powerfully conveys his feelings of despair and helplessness after losing his love.
Most breakup songs find somebody to blame. This one doesn't. The singer spends three minutes admitting the whole thing was his own doing, opening with "Sé que te marchaste sin saber" (I know you left without knowing) and never once letting himself off the hook: "Hoy me avergüenzo, fui el motivo de tu llanto" (today I'm ashamed, I was the reason you cried). The title is the confession. "Soy un idiota, te perdí" (I'm an idiot, I lost you) comes back four times, and he means it as a verdict rather than as a way of sounding humble.
The images he reaches for are big and physical. There is "una daga envenenada aquí en mi pecho" (a poisoned dagger here in my chest), and later "hoy naufrago en este mar de tu abandono" (today I'm shipwrecked in this sea of your leaving). The verse that stings most is the one where he wishes somebody else on her: "Sé que otro amor encontrarás" (I know you'll find another love), a love that will give her "todo lo que yo no supe darte" (everything I never knew how to give you). Then "Ni yo me perdono" (I don't even forgive myself), and the chorus starts over.