Guest Hobbles, might you be looking for this: a song that has a very simple melody line (the sort that makes a good round) and the words are (I do not speak Spanish)
--mos el barco,
-- -- -- --
four short lines, each rising up a four note bit of scale,The melody has the short four lines above, then switches to the higher key related tune (rather the way reels do) for another four, each going down in pitch.

and translates (the chorus anyway)
"You are the boat, I am the sea,
I live in you, you live in me"
I do not know the song myself (obviously) but know someone who sings it and could give him a call. (He is not a regular here.)