Taiwan’s prototype indigenous submarine, named “Haikun,” carried out its first submerged test on 26 January 2026, marking a milestone for a program that has been dogged by schedule slippage and technical teething problems. The dive comes more than a year after the vessel began shore trials and several months after its initial sea trials, underscoring the challenges of fielding a modern conventional submarine in-house.
The Haikun’s development timeline, as reported in Taiwan’s media, has been uneven. The hull was moved from the contractor’s factory to a small dock on 27 February 2024 and later berthed at Kaohsiung’s berth 91 for shore testing on 15 July 2024. The boat first transited under its own power in Kaohsiung harbor on 14 June 2025 and undertook its first sea trial on 17 June 2025; however, until 28 November 2025 it had only completed surface-navigation tests and had not yet submerged.
Under the contract, the submarine was originally due to be delivered following sea trials in November 2025, a deadline Taiwanese defence officials subsequently acknowledged could not be met. Taipei has applied contractual penalties to the shipbuilder—reported at NT$190,000 per day—and set a new internal target of June 2026 for handover. Officials and industry sources attribute the principal cause of the delay to problems integrating the submarine’s platform management system with onboard sensors and weapons, a software and systems-integration issue rather than propulsion or basic hull deficiencies.
The Haikun’s delayed dive and remaining test program highlight the complexity of modern undersea warfare platforms. Full certification still requires a sequence of staged trials, including snorkel-depth testing, shallow-water dives and deep-water dives, which will take several more months to complete. If the programme follows the timetable cited by Taiwan’s shipbuilder—using foreign precedents as reference—the full test cycle may extend into mid‑2026 or longer.
For Taipei, the submarine programme is both a capability project and a political symbol. Diesel-electric attack submarines are central to Taiwan’s asymmetric defence posture because a small fleet of quiet boats can complicate Beijing’s potential maritime operations. Delays therefore bear practical implications for Taiwan’s deterrent capacity and political consequences for a government keen to show progress on defence self-reliance.
The technical problems cited—chiefly systems integration between the integrated platform management system and combat and sensor suites—are not trivial. They reflect the difficulty of marrying complex software, electronics and weapons interfaces in a platform designed to operate in a contested littoral. How quickly Taiwan’s shipyards and systems suppliers can resolve those issues will determine whether the Haikun becomes a credible addition to the island’s undersea force in the near term or a protracted programme that requires outside assistance or design changes.
The Haikun’s progress will be watched closely by regional and global actors. For Beijing, any indigenous submarine capability developed by Taipei is strategically sensitive; for Washington and partners, Taiwan’s ability to field effective asymmetric systems influences alliance planning and regional deterrence calculations. The next months of testing will therefore carry outsized strategic weight beyond the purely technical questions of hull, engine and electronics integration.