What is "marenariello"

"Marenariello" is a Neapolitan song written in 1893 by Gennaro Ottaviano (words) and Salvatore Gambardella (music). It was adapted into the English language hit " I Have But One Heart" and was sung by Andrea Bocelli on his first classical album Viaggio Italiano released in 1997. A Dutch version, "Het vissermeisje", was a hit in the 1930s for Joseph Schmidt.