Italian submarine Comandante Cappellini was a World War II Italian Marcello-class submarine built for the Italian Royal Navy (Italian: Regia Marina). After Italy's surrender, the submarine was captured by the Japanese and handed over to Germany as UIT-24. Following the capitulation of Germany, the Japanese integrated the boat into their fleet as I-503 (Japanese: 伊号第五百三潜水艦). Following the end of the war, the United States scuttled the submarine in 1946.