Taiwan’s first domestically built submarine to complete trials by mid-2026

Taiwan’s first domestically constructed submarine, the Hai Kun (Narwhal), is expected to complete sea trials no earlier than mid-2026, the Taipei Times reports.

The submarine was scheduled to enter active service with Taiwan’s navy in November 2025. It is set to begin its first underwater trials on January 26, according to the newspaper, citing information from the shipbuilder CSBC Corp.

The company noted that submarine testing procedures are highly complex and often take significant time, especially for prototypes. “ [...] submarine testing procedures are highly complex and often take a very long time — especially for a prototype vessel, which, based on foreign experience, can sometimes take more than a year,” CSBC said.

The Hai Kun is expected to undergo three cycles of underwater trials: at periscope depth, in shallow water, and at deep-sea levels.

According to the Taipei Times, initial plans reported in February 2025 had envisaged sea trials starting in April of that year, with completion by September and commissioning in November. However, construction and testing took longer than expected. The submarine first entered the water for surface trials on June 17, 2025, which have only now been completed.

Taiwanese authorities have approved plans to build a further seven Narwhal-class diesel-electric submarines at a Kaohsiung shipyard, though the implementation of these plans will depend on the success of the first vessel.

By Vugar Khalilov