New discoveries uncover how the Romans ruled the seas for four centuries. Archeologists dive a small cargo ship wrecked off Sukosan, Croatia, from the 1st Century CE; test two replica small river patrol boats in Gunzenhausen, Germany, from the 2nd and 4th Centuries CE; and explore the Roman harbor at Puteoli, Italy, the largest transit port for Rome at the beginning of the 1st Century CE.