Hai Kun-class submarine
The Hai Kun-class submarine (, translation "Narwhal"), alternatively known as the Indigenous Defense Submarine (IDS) program, is a class of attack submarines built by CSBC Corporation, Taiwan for the Republic of China Navy. While the Hai Kun class is thought to be based on the Dutch Zwaardvis class, which is currently operated by Taiwan, the design has been brought up to date by incorporating many new and more modern systems. History
Since 2001, Taiwan has been attempting to procure new submarines to bolster its aging underwater fleets, which consisted of two Dutch-built  submarines from the 1980s and two US-built GUPPY-class submarines that saw action in the Second World War. In 2003, the US offered to provide the subs for Taiwan, but as the US has not been building diesel-powered submarines since the 1950s, and after an offer of eight refurbished Italian Nazario Sauro-class submarines was declined by Taiwan due to their age, the attempt to acquire foreign-built submarines was set aside in favor of domestic options. The Ministry of National Defense announced in 2014 that Taiwan will construct its own diesel-electric attack submarines (SSKs) with help from the United States, and in 2016 a submarine development center was established by CSBC Corporation, Taiwan to oversee the Indigenous Defense Submarine program under the code name "Hai Chang" (). In April 2018, President Donald Trump approved the technology transfers that would enable Taiwan to build its own submarines, and in the following years multiple design proposals from countries that reportedly includes India and Japan were considered. Design
In May 2019, Taiwan revealed a scale model of its chosen design for an indigenous built diesel-electric attack submarine. The boats will be assembled using Japanese construction techniques in Taiwan. A Japanese team consisting of retired engineers from Mitsubishi and Kawasaki Heavy Industries is believed to have provided technical support. Reportedly, a version of the AN/BYG-1 submarine combat management system, used in US Navy nuclear submarines, is being offered to Taiwan. The design of the Hai Kun class is thought to be derived from the Dutch , which is currently operated by Taiwan, with some similarities to the Dutch  as well. The submarine features a hybrid double-single hull structure with a light outer hull, but replaces the cruciform control surfaces of the Zwaardvis class with the more prevalent X-form type rudders, resembling Japan's  and the Dutch Walrus-class SSKs. It does not feature air independent power (AIP) and is believed to lack anechoic coating. When it comes to speed, the submarine will likely reach a surface speed of 8 knots and a submerged speed of 17 knots. In addition, it has a expected range of up to 11,000 kilometers. The vessels are estimated to be in the ~2,500-ton class and  in length. CSBC Corporation, Taiwan was awarded a contract to build eight submarines. The initial project contract is for US$3.3 billion with projected procurement costs of US$10bn for a fleet of ten boats. The first submarine of the class, Hai Kun, is estimated to have cost approximately 1.54 billion dollars. It is estimated that around 40% of the boat features domestic content. In October 2019 it was reported that construction of the class would commence at the Heping Island yard in Keelung (Northeast Taiwan) rather than in Kaohsiung (Southwest Taiwan). Later in October 2019 it was reported that personnel working on the project were forbidden from traveling to or transiting through Macao or Hong Kong (their travel to Mainland China had already been restricted) due to security concerns. Construction
In May 2020, the United States Department of State approved the sale of 18 MK-48 Mod6 Advanced Technology Heavy Weight Torpedoes and related equipment to Taiwan for an estimated cost of $180 million. In November 2020, President Tsai Ing-wen opened the submarine construction facility in Kaohsiung (not Keelung) with plans to build eight submarines. Construction was to begin with a prototype boat which was to be built over 78 months. Anticipated delivery was in 2025, though a 78-month build time suggested a somewhat later delivery. Between December 2020 and February 2021, the United States reportedly approved the export of three key systems to Taiwan for the program: digital sonar systems, integrated combat systems and auxiliary equipment systems (periscopes). In 2021 it was announced that the production timeline had been moved up with the prototype vessel expected to be launched in September 2023. The ceremonial keel laying of the lead boat was reported to have occurred in November 2021. In mid-2022 it was reported that the launch of the first submarine remained on track for September 2023. The date for service entry was still envisaged as 2025. In November 2021 Reuters reported that Taiwan had recruited engineers and retired submariners from the US, UK, Australia, South Korea, India, Spain and Canada to work on the program and advise the navy. The UK government has granted licenses to companies to export some £167 million worth of submarine technology and parts to Taiwan, more than the prior six years of investment since 2017 combined. Current and former UK officials have warned against disclosing specific information about support given to Taiwan publicly. In May 2023 CSBC Corp. announced that the prototype would undergo final tests in September of that year. On 21 September 2023, the launch date was confirmed to be 28 September 2023, and the name of the first boat and hull number were announced. The first boat will be named Hai Kun, after a mythological fish mentioned in the ancient Chinese text Zhuangzi, written during the Warring States period by Zhuang Zhou, which was described as being of an unfathomable size. The hull number was given as SS-711, as the existing numbers remaining if continued from the Hai Lung-class's Hai Hu (SS-794) would not accommodate the planned eight boats. After launch harbor acceptance trials will start on 1 October 2023 and preliminary evaluations are expected to be completed by 1 April 2024. Following the launch Kuomintang politician Ma Wen-chun was publicly accused of attempting to hinder Taiwan's domestic submarine program through outing foreign individuals involved in the program and through providing information on the program to the People's Republic of China. Following comments by the head of the submarine program about an unspecified legislator who had interfered with the program Ma posted on Facebook “If you name me, I’ll have to sue you” following which she was named by her legislative colleagues. Boats

See also 
 Defense industry of Taiwan

Submarines of similar comparison 
 Type 212 submarine - A class of diesel-electric attack-submarines developed by ThyssenKrupp Marine Systems and exclusively built for the German Navy, the Italian Navy and the Royal Norwegian Navy. Type 214 submarine - A class of export-oriented diesel-electric attack-submarines, also developed by ThyssenKrupp Marine Systems and currently operated by the Hellenic Navy, the Portuguese Navy, the Republic of Korea Navy and the Turkish Naval Forces. Type 218SG submarine - A class of extensively-customised diesel-electric attack-submarines developed ThyssenKrupp Marine Systems and currently operated by the Republic of Singapore Navy. - A class of extensively-customised diesel-electric attack-submarines developed by ThyssenKrupp Marine Systems and currently operated by Israel. - A unique class of  diesel-electric attack-submarines developed by ThyssenKrupp Marine Systems and currently being built for Israel. - A class of export-oriented diesel-electric attack-submarines, jointly developed by Naval Group and Navantia and currently operated by the Chilean Navy, the Royal Malaysian Navy, the Indian Navy and the Brazilian Navy. S-80 Plus submarine - A class of conventionally-powered attack-submarines, currently being built by Navantia for the Spanish Navy. is a class of submarine developed by Kockums for the Swedish Navy
 KSS-III submarine - A class of diesel-electric attack submarines, built by Daewoo Shipbuilding & Marine Engineering and Hyundai Heavy Industries and operated by the Republic of Korea Navy. - A class of diesel-electric attack submarines currently being built by Mitsubishi Heavy Industries and Kawasaki Heavy Industries for the Japan Maritime Self-Defense Force
 Type 039A submarine - A class of diesel-electric attack-submarines operated by the People's Liberation Army Navy (China) and being built for the navies of the Royal Thai Navy and the Pakistan Navy. - A class of diesel-electric attack-submarines being built for the Russian Navy. References

Attack submarines
Submarines of the Republic of China Navy
Submarine classes