Taiwan’s domestically built prototype submarine, the Haikun, conducted its first submerged test on 26 January 2026, marking a milestone in a programme dogged by schedule slippage. The event follows a protracted sequence of shore and surface trials that began when the vessel was moved from its construction hall in February 2024 and entered dock-based testing in July 2024.
The programme’s timeline has been uneven. The Haikun first demonstrated autonomous propulsion in Kaohsiung harbour in June 2025 and undertook initial sea trials shortly afterwards, but up until late November 2025 the boat had only performed surface navigation tests. An original contract required sea-trial completion and delivery by November 2025, a date that Taipei’s defence authorities acknowledged could not be met, triggering contractual daily fines for the shipbuilder.
Engineers and programme managers now face a sequence of critical submerged evaluations: snorkel-depth (breathing tube) trials, shallow-water depth checks and deep-water depth trials. Industry sources cited integration problems with the submarine’s integrated platform management system, which has proven unable to link smoothly with the vessel’s sensors and weapons—a technical snag that programme stakeholders identified as the principal cause of the delivery delay.
The shipbuilder and defence authorities have set an internal delivery target for June 2026, but that timetable remains conditional. Observers point to foreign precedents in which full test regimes for prototype submarines have stretched beyond a year; if Taiwan follows similar patterns for progressive safety and weapons integration checks, operational handover could yet be months away.
The Haikun programme is more than a domestic industrial exercise. Taipei regards an indigenous submarine capability as a core element of its asymmetric deterrent, complicating any aggressor’s calculus in the Taiwan Strait. Delays reduce the near-term expansion of that capability and impose political and budgetary strains on an already stretched defence modernisation effort.
For Taiwan’s naval shipbuilding sector the Haikun reveals the twin realities of maturity and challenge: local firms can design and produce advanced hulls, but integrating complex combat and sensor systems remains a steep learning curve. The outcome of the remaining test phases will determine whether the submarine can transition from prototype to credible operational asset or whether further retrofits and trials will be required, with knock-on effects for procurement schedules and regional deterrence dynamics.