Sumergido translates to "submerged" or "immersed". It's a vivid and somewhat dramatic word that paints a strong picture.
In the song, the artist uses it to describe a past state of being, singing "Es como si nunca hubiera estado sumergido en otros brazos" (It's as if I had never been submerged in other arms). This metaphor beautifully conveys a feeling of being completely enveloped and lost in previous relationships, highlighting the profound difference of his current love.
Andrés Cepeda's "Esto No Se Llama Amor" is a beautiful, heartfelt song about finding a love so profound it redefines everything you thought you knew about romance. He sings about how his partner's touch and kisses make life begin again, making him forget any past relationships. He even says, "Me enciendes desde el alma a los pies" [You light me up from soul to feet].
He's so overwhelmed by this new feeling that he admits, "De tanto placer se me aguan los ojos" [From so much pleasure my eyes water]. He thought he knew everything about love, but this new experience is "mejor de lo que había sentido" [better than what I had felt], "mucho más grande, más fuerte, más vivo" [much bigger, stronger, more alive]. It's a love that "me ataca y me llega a los huesos" [attacks me and reaches my bones], so perfect and far from pain that he doesn't want it to end, even though it's completely tangled in his soul and body.