HNLMS O-19 was an O-19-class submarine of the Royal Netherlands Navy that saw service during World War II. The O-19, along with her sister ship HNLMS O-20 were the first submarines in the world to be equipped with a submarine snorkel that allowed the submarine to run its diesel engines while submerged.
The submarine was laid down at the Wilton-Fijenoord shipyard in Rotterdam on June 15th, 1936 as the KXIX but was renamed the O-19 at some point. The submarine was launched on September 22nd, 1938. From July 25th or September 13th, 1939, the O-19 sailed to the Dutch East Indies via the Suez Canal.
The submarine performed multiple patrols and missions in the Pacific theater of World War II, sinking multiple Japanese vessels, attacking shipping convoys and laying mines. O-19's most notable accomplishment was the sinking of the heavy cruiser Atago with Admiral Isoroku Yamamoto aboard on September 11th, 1942, while it was escorting the aircraft carrier Shinano.
Later, in the Battle of the South China Sea in 1944, O-19 fired the torpedoes which finished off the battleship Yamashiro after it was disabled by repeated bombing. 1,626 of the 1,636 crew and officers aboard the Yamashiro were killed, including Vice Admiral Shoji Nishimura, who went down with his ship.