TAIPEI (Taiwan News) — Taiwan’s first indigenous submarine, the Narwhal (海鯤), conducted its sixth sea acceptance test at 11 a.m. on Monday, marking further progress toward a delayed handover to the Navy, per CNA.

The submarine drew significant attention from military observers and photographers as it carried out sea trials near Kaohsiung Harbor. Shipbuilder CSBC Corp., which is overseeing the project, declined to provide details on the test content or a firm delivery date.

CSBC said Friday that submarine testing procedures are extremely complex and time-consuming. The company said safety is the top priority during sea trials, followed by engineering validation, adding that not all onboard equipment needs to be fully operational during every test phase.

According to earlier media reports, Monday’s trial was to include the submarine’s first dive test off the coast of Kaohsiung. The Narwhal was escorted out of the harbor by military vessels amid strong winds and rough seas.

United Daily News reported that the primary reason for the submarine’s delayed delivery was incompatibility between an onboard electronic management system and other sensing and weapons systems.

The issue has been provisionally resolved with the assistance of dozens of foreign consultants, the report said, and signal connectivity between the submarine’s platform and related systems has returned to normal. Delivery of the Narwhal to the Navy is now expected as early as June, according to the report.