During the interwar period, the renowned Italian decorator Giulio Rosso is involved in projects of interior decoration of two important ships: the Aurora, which was the private yacht of the Head of Government, and the Conte di Savoia, which was the first Italian ocean liner to boast a prevalently modern interior design. Thanks to the collaboration with architects such as Melchiorre Bega and Gustavo Pulitzer Finali, who championed a functional design that did not exclude decoration, Rosso contributed to the renewal of naval design. In the final part of this essay, I advance the attribution to Rosso, once again in collaboration with Bega, of some interior decoration of the Diana, the yacht that was supposed to replace the Aurora.