The island is divided into eight communes : Portoferraio , Campo nell ` Elba , Capoliveri , Marciana , Marciana Marina , Porto Azzurro , Rio Marina and Rio nell ` Elba . The island is divided into eight municipalities , of which Portoferraio is the main one , the others ; Campo nell ` Elba , Capoliveri , Marciana , Marciana Marina , Porto Azzurro , Rio Marina , and Rio nell ` Elba , are part of the province of Livorno , with a total of about 30,000 inhabitants , which increases considerably during the summer .