Taiwan’s domestically built submarine Hai Kun returned to Kaohsiung on January 26 for its sixth sea trial but did not carry out its long‑anticipated first dive, remaining instead in a “pre‑dive” verification phase. The shipbuilder, referred to in local reporting as 台船, said the day’s activity comprised an integrated systems check ahead of a full submergence. Observers at the dock said the verification was complex, and sources signalled that a formal dive is likely to follow soon, though no date was announced.
The Hai Kun programme has missed multiple internal milestones. The submarine was originally slated to begin sea trials in April 2025 and to be handed over by November 2025; the first sea trial did not occur until June 2025. By November 28, 2025, the vessel had completed a fifth floating test covering propulsion, air conditioning, navigation instruments, communications, the periscope and sonar. It then entered dock on December 5 for system checks and calibration intended to pave the way for dive trials.
Pressure is mounting on the shipbuilder because of the slippage. Taiwan’s defence overseer Gu Li‑xiong confirmed that the government is enforcing the contract’s liquidated damages, levying NT$190,000 per day in fines. The shipyard has downplayed the January 26 setback: while it did not submerge, it completed pre‑dive preparations at the quay and said a formal dive is imminent. Local media reports that the programme is still racing to hit an internal June delivery target.
The delays matter beyond a single procurement timetable. Taipei has framed the Hai Kun project as a strategic priority: an indigenous conventional submarine would strengthen asymmetric deterrence by complicating Beijing’s maritime calculations and by providing a locally controlled platform for intelligence, sea denial and potential offensive operations. Building submarines is technically demanding, and Taiwan’s industrial base is executing a politically sensitive, high‑stakes learning curve after decades of relying on foreign designs and supply chains.
Completion timing will shape not only Taiwan’s near‑term naval posture but also political debates about defence procurement and industry capability. Continued slippage could force Taipei to reconsider timelines for activating the boat in an operational squadron, to reallocate budgets for additional repairs or upgrades, or to seek external technical assistance that could carry diplomatic or security trade‑offs. For Beijing, any further postponement is likely to be cast as evidence of Taipei’s industrial weakness, while a successful imminent dive would be spun in Taipei as a demonstration of growing self‑reliance.
For international observers, the story is a reminder that capability‑building projects take place at the intersection of engineering, procurement and geopolitics. The Hai Kun programme will be judged not only on the date it first submerges but on how reliably it can be maintained, how quickly a crew can be trained to operate it in contested waters, and whether Taiwan can scale the capability beyond a single hull.