This beautiful stamp from the Royaume du Cambodge (Kingdom of Cambodia), issued in 1959, commemorates the development of the deep-sea port at Sihanoukville, named after Prince Norodom Sihanouk. The design features a map of the port area, a ship entering the harbor, and a portrait of Prince Sihanouk, symbolizing Cambodia’s modernization and economic progress during his reign. The 5 Riels denomination was part of a definitive or commemorative set highlighting national infrastructure projects that linked Cambodia to global trade routes.