Hr. Ms. K XII was a Dutch submarine of the K XI-class. The construction began on January 9, 1923, at the Fijenoord shipyard in Rotterdam. The ship was intended for service in the then Dutch East Indies. On July 15, 1924, the submarine was launched, and it was commissioned on May 19, 1925. On September 19, 1926, the K XII left Den Helder for the Dutch East Indies, where it arrived in Surabaya on December 28, 1926.

 World War II
In early 1941, the K XII was assigned to the 2nd Division of the Submarine Flotilla in the Dutch East Indies, along with the K X, K XI, and K XIII, all stationed in Surabaya.

From December 9, 1941, to February 1943, the K XII operated under British operational command from Singapore. During a retreat after a patrol west of the Anambas Islands (Malaysia), the submarine rescued nine survivors from a downed British PBY Catalina flying boat.

The three patrols carried out by the K XII under British command were unsuccessful. Returning under Dutch command, the submarine undertook one more patrol southeast of Sumatra, which also ended in failure.

On March 6, 1942, the K XII was one of the last ships to escape from Surabaya to Fremantle (Australia), where it safely arrived on March 20, 1942. From Australia, the submarine carried out special operations, including dropping off and picking up agents who were active in the Japanese-occupied Dutch East Indies.

Australia
The K XII, along with the K IX and their crews, was made available by the Royal Netherlands Navy to the Royal Australian Navy for training in anti-submarine warfare.

From June 1943 to February 1944, the K XII was used as a target ship for ASDIC training (underwater sonar). On March 22, 1944, the submarine was transferred to Sydney. In May 1944, the K XII was officially decommissioned.

 
Museum Ship and Final End
In 1946, the former submarine was sold to private owners, who operated it as a museum ship in Manly Bay (Sydney). After a severe storm in June 1949, it was decided to tow the ship to a safer location, Neutral Bay. However, the tow cables broke, and the ship ran aground at Fairlight Beach.

The hull was later raised and, on January 7, 1951, was re-floated by scrap metal traders. According to a newspaper report from January 8, 1951, the hull was then sold as scrap.

A letter from the historical department of the Dutch Navy, dated July 1952, states the following:

"She had been handed over to the disposal committee. She blew ashore in Sydney Harbour in 1950 and became scrap."
However, there is also a report that part of the hull sank again, this time near the Ryde Road Bridge in the Parramatta River in Sydney. After the hull was lightened, it was towed to this location, but it sank again after the seacocks (underwater valves) were vandalized.

Stranded

In 1946, the ship was sold to private individuals who operated it as a museum ship in Manly Bay. After a storm in June 1949, it was decided to tow the former submarine to a safer location (Neutral Bay). However, the cables snapped, and the ship ran aground at Fairlight Beach. The hull was raised and refloated by scrap metal dealers on January 7, 1951. According to a newspaper report from January 8, 1951, the hull was sold for scrap. This agrees with an letter from the historical department of the Dutch navy from July 1952: 'She had been handed over to the disposal committee. She blew ashore in Sydney Harbour in 1950 and became scrap.'¹

But there are also reports that: The hull was lightened by salvagers then re-floated on 7 January 1951, and towed up the Parramatta River to Ryde Road bridge; however here she sank again after her seacocks were vandalised.²

Armament: The boats of the K XI class were equipped with two 533 mm (21 in) torpedo tubes and four 450 mm torpedo tubes. In total, the boats could carry 12 torpedoes, that is, all tubes were loaded and each tube had one torpedo for reloading. The following torpedoes were used on the ships of the K XI class: the 450 mm III45, the 533 mm I53, and the 533 mm II53. In addition to torpedoes, the boats were equipped with an 8.8 cm Bofors gun and a 12.7 mm machine gun.

• defensieweb.fandom.com.
• Fairlight.
• Mike McCarthy.
  Jervoise Bay shipwrecks.
• Dutch Submarines.
  Article on the K XII at Dutchsubmarines.com.