The Type 3 submergence transport vehicle (三式潜航輸送艇 San-Shiki Senkō Yusōtei?) was a class of transport submarines of the Imperial Japanese Army (IJA), serving during the Second World War. The IJA planned to build over 400 boats, however only 38 boats were completed until the end of war. The IJA called them Maru Yu (マルゆ?).