Type J1 submarine
 The Type J1 submarines were large cruiser submarines of the Imperial Japanese Navy.Four boats were built between 1926 and 1929. These boats based on the KD2 and U-139 designs were of a junsen or cruiser type with an impressive range of 24000 nm. Elderly by 1941 they were among the first Japanese submarines converted to supply duty. I-1 was present during the attack on Pearl Harbor and witnessed the Doolittle raid on Tokyo before patrolling the Aleutians.