Taiwan's Silent Fleet: The Secretive 256 Submarine Squadron

Taiwan has invested NT$50 billion (approx. US$1.54 billion) into building the indigenous submarine Hai Kun (海鯤號), which is currently undergoing an intense phase of Sea Acceptance Trials (SAT). As technical teams from the Taiwan Shipbuilding Corporation (CSBC) and foreign experts put the new vessel through its paces, the Navy's 256 Squadron is quietly working alongside them, mastering every system they will soon operate in combat.

Unlike surface fleets with multiple formations, the 256 Squadron is Taiwan's only submarine unit—a "silent fleet" as difficult to detect in public life as its boats are at sea. Within the Navy, however, its status is unmistakable. Submarine officers are considered the elite among elites, selected through brutal screening and rigorous testing before earning the right to wear the submarine insignia.

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An Elite Unit with Unforgiving Entry Tests

The 256 Squadron is Taiwan's sole submarine warfare force, commanded by a rear admiral and operating two combat-ready Sword Dragon-classsubmarines alongside two Guppy-class boats used for training. Veterans note that the unit cultivates a distinct professional pride rooted in the difficulty and isolation of their work. To maintain a "pure" and elite officer corps, all 256 Squadron officers must graduate from the Naval Academy's regular program, as reserve or professional officer tracks are not accepted for these roles.

Even among Academy graduates, the selection is highly competitive, as only those ranking in the top third of their class are eligible to apply. In a typical year, approximately 60 candidates compete for as few as eight slots. The process includes exhaustive medical checks and specialized hearing tests using high- and low-frequency equipment to map a candidate's auditory range. Furthermore, a pressure-chamber test ensures the candidate's body can withstand the physical rigors of deep-sea depth changes.

The final oral interview is designed to expose mental flaws that written tests cannot. One former submarine general recalls a psychological environment where candidates must remain composed even in emergencies. In some cases, candidates were asked for their views on "opposition party mayors" to test their reaction time and decisiveness under pressure, where any hesitation could lead to immediate elimination.

​High-Stakes Training: A Life-or-Death Job

​Submarine training is significantly more rigorous than that of the surface fleet. While a surface officer might require 15 weeks of advanced training for promotion, submarine officers undergo six months of classroom instruction alone before their first navigation experience. Following classroom work, candidates face a long period of on-the-job training and more than 200 individual checks on everything from engine starts to emergency breakdowns. Only after passing a final comprehensive oral exam do they receive their Personnel Qualification System (PQS) certification.

​​The stakes are brutally simple: if an aircraft fails, it crashes; if a submarine fails, it does not surface. One officer described the role bluntly as a job where one is literally playing with their life. This extreme danger is reflected in their pay, as submarine personnel receive some of the military's highest allowances, second only to pilots.​

Mastering the Hai Kun

Today, the 256 Squadron serves as the core crew learning to operate the Hai Kun. They act as "apprentices" to foreign technical advisors, moving from classroom theory to simulators and eventually to live shipboard operations. Unlike surface ships, which can be handed over later in the building process, the Hai Kun requires its crew to be involved early due to the complexity of its systems. This requires the first crew to spend extensive hours in simulators and even stay aboard overnight to monitor the boat's status. （Related： The Navy Unit No One Talks About — And Can't Afford to Lose ｜ Latest ）

Within the Navy, many believe that a fleet without submarines is like a body missing a leg. As the Hai Kun progresses through trials, the "silent fleet" of the 256 Squadron continues to master the vessel away from the spotlight. At a time of rising geopolitical tension, their goal is to turn this indigenous boat into a credible undersea deterrent to safeguard Taiwan.