The Moonta was launched in June 1931 Burmeister & Wain shipyard in Copenhagen, Denmark for the Adelaide Steamship Company. She started service with a six-day itinerary, disembarking in Adelaide and ending in Port Lincoln, usually with four or five calls along the way. Moonta became well known and beloved for her excellent service and relaxing voyages, being called the perfect "romantic holiday" ship. After serving in World War II the Moonta continued her Australian coastal service until 1955, when Moonta was sold to the Greek Hellenic Mediterranean Lines for cruising. With this her new owners doubled her passenger capacity and renamed her Lydia. She remained in Greek cruise service until 1966, when Hellenic Mediterranean laid her up.