TAIPEI (Taiwan News) –  The domestically built Narwhal submarine conducted its fourth sea test on Thursday morning in Kaohsiung.

A crowd of military enthusiasts cheered the submarine, waving flags and holding banners that read "Go Navy!"  The test was conducted with heavy security as the submarine sailed out of Kaohsiung Harbor, per CNA.

Military analyst Chi Tung-yun (紀東昀) told reporters the Narwhal is expected to carry out sea acceptance tests outside the harbor, in deeper waters near Xiaoliuqiu. He noted that harbor restrictions limit vessel speeds to around 10 kph, making open-sea testing essential.

Chi said personnel typically conduct deployment and preparedness tasks on deck as vessels enter or leave port, but once the submarine cleared the harbor, all crew members moved inside. The Narwhal then flooded its stern section to increase propeller efficiency as it headed into open waters.

The submarine previously completed harbor acceptance tests and had been scheduled to finish sea testing in September. Under the original timeline, CSBC Corporation, the builder, was to deliver the vessel to the Navy in November.

However, Defense Minister Wellington Koo (顧立雄) recently said completing tests and delivering the submarine by November remains “a considerable challenge.” Missing the contracted deadline would trigger a daily fine of about NT$190,000 (US$6,500).

Once the Narwhal prototype is successfully delivered, the Navy plans to order seven additional submarines from CSBC for NT$284 billion (US$9.26 billion).