The I-25 was a Japanese submarine whose keel was laid in 1939, launched in June 1940, and commissioned in the Imperial Japanese Navy in 1941. The length of the ship at the time of launching was 108.7 m, width 9.3 m, and the underwater displacement - 3,300 tons. The maximum surface speed of the I-25 reached 23.5 knots on the surface. The main armament was six 533 mm torpedo launchers, and the secondary armament was a single 140 mm gun and two 25 mm Type 96 anti-aircraft guns. The ship also took one Yokosuka E14Y seaplane on board.
The I-25 was an ocean submarine of the B1 type, which in many design solutions was based on the Kaiden type, especially the KD6 type. However, it differed from its ancestors in size, especially in the underwater and surface displacement, as well as in the immersion depth, which increased to about 100 meters. Type B1 ships were also equipped with seaplanes, which gave them greater possibilities in terms of sea reconnaissance, they were also characterized by a large range and high surface speed. The I-25 began her participation in the war in the Pacific by patrolling the waters of the island of Oahu in the course of the Japanese attack on Pearl Harbor on December 7, 1941. In February and March of the following year (1942) I-25 operated in the South Pacific in the Sydney and Melbourne area of Australia. In May 1942, the ship was directed to the Aleutów region, receiving mainly reconnaissance tasks. In turn, in the second half of 1942, I-25 was directed towards the western shores of the USA. The ship was sunk on September 3, 1943 as a result of a depth charge attack by destroyer USS Ellet in the New Hebrides area.