Taiwan tests first domestically built Hai Kun submarine
Taiwan has begun the first dive tests of its domestically built submarine Hai Kun (SS-711), marking a new phase in the island’s indigenous submarine program.
According to Taiwan’s Liberty Times and other local outlets, the submarine conducted its initial submersion test on Sunday, moving beyond surface and harbor trials that have taken place over the past year. The test marks the first time the vessel has entered controlled underwater trials since construction was completed.
The Hai Kun is Taiwan’s first domestically constructed submarine and a central element of the island’s plan to strengthen undersea deterrence in the Taiwan Strait. The vessel began land-based testing at Kaohsiung port in July 2024 after being launched earlier that year.
During earlier trials, the program encountered technical setbacks. In September 2024, the submarine reportedly suffered a main engine failure during sea trials after a rupture in internal piping systems. Following repairs, the submarine resumed testing with departure trials in June 2025 and completed floating tests in November, according to Taiwanese media.
The January dive test initiates a new sequence of trials that will evaluate the submarine’s performance at different depths. Local media reported that Taiwan’s defense authorities expect the full testing program to be completed by mid-2026, clearing the way for formal delivery to the navy.
Taiwan’s Ministry of National Defense is targeting June 2026 for the submarine’s handover, roughly seven months later than originally planned. Sources cited by local outlets said the delay was primarily caused by problems with the integrated platform management system, which initially failed to link effectively with other onboard sensor systems.
A source told Taiwanese media that the technical issues were resolved with assistance from foreign engineers, after which signal connections between the submarine’s systems were restored and functioned normally. Officials have not disclosed the identities of the foreign specialists involved.
The Hai Kun is the lead boat of a planned class of eight indigenous submarines that Taiwan aims to build and deploy by 2027. The program is intended to provide Taiwan with a survivable undersea force capable of complicating Chinese naval operations in the event of a conflict.
The start of dive testing places the Hai Kun among the most closely watched naval programs in the region, as Taiwan works to reduce reliance on foreign-built platforms and increase domestic defense production in key areas.
