On the overcast morning of November 27, 2025, the docks at Gölcük Naval Shipyard were the stage for a defining moment in Mediterranean naval history, as the Turkish Navy formally accepted the TCG Hızırreis (S-331) into its ranks. The ceremony, attended by high-ranking officials from the Defence Industry Agency (SSB), naval command, and representatives from Germany’s ThyssenKrupp Marine Systems (TKMS), marked the conclusion of a rigorous testing phase and the beginning of a new chapter for Ankara’s undersea warfare capabilities. This delivery, coming just over a year after the commissioning of the lead boat TCG Piri Reis, is far more than a routine fleet update; it serves as a tangible confirmation that Türkiye’s ambitious New Type Submarine Project (YTDP) has overcome past hurdles and is now delivering cutting-edge assets on a reliable schedule. For the balance of power in the Black Sea and the Eastern Mediterranean, the arrival of the Hızırreis signals that the Turkish Navy is rapidly transitioning from a localized coastal defense force into a formidable regional power with deep-strike reach.
The TCG Hızırreis represents the second of six planned Reis-class submarines, a variant of the renowned German Type 214 design that has been heavily modified to meet specific Turkish requirements. While the external silhouette might resemble its German cousins, the internal reality of the S-331 is a hybrid of proven hull engineering and indigenous electronic sophistication. Roughly 80 percent of the work on the submarine was completed locally, a statistic that underscores Ankara’s drive for defense autonomy. Companies like STM, Aselsan, Havelsan, and MilSOFT have packed the vessel with Turkish-made subsystems, ranging from the combat management suite to the integrated sonar networks. This localization means that while the steel may be cut to a German design, the brain and nervous system of the boat are distinctly Turkish, allowing for easier upgrades and independence from foreign operational restrictions in times of crisis.
Technologically, the Hızırreis is a leap forward from the older diesel-electric models that have long populated the region’s navies. The core of this advantage lies in its Air-Independent Propulsion (AIP) system, which utilizes polymer electrolyte membrane fuel cells alongside high-capacity batteries. In practical terms, this allows the submarine to operate without the “snorkeling” requirement that plagues traditional diesel boats—the dangerous need to surface or raise a mast to recharge batteries, which exposes them to radar and visual detection. The Hızırreis can remain submerged for weeks at a time, gliding silently through the deep at depths estimated between 300 and 400 meters. This capability transforms the vessel into a silent sentinel, able to lie in wait at strategic choke points like the Dardanelles or the contested waters of the Aegean without giving away its position. Its low acoustic signature, achieved through a hydrodynamically refined hull and quiet electric drive, makes it a nightmare for opposing anti-submarine warfare units to track.
However, a submarine is only as effective as the weaponry it carries, and here too, the Hızırreis reflects a shift in doctrine. The boat is equipped with eight 533mm torpedo tubes capable of launching a mix of legacy munitions and next-generation Turkish weapons. Among these is the Roketsan-made Akya heavy torpedo, a high-speed, fiber-optic guided weapon designed to break the backs of enemy surface ships. Even more significant is the integration of the “Sub-Atmaca” anti-ship missile, which allows the submarine to strike surface targets from standoff ranges, and the future promise of the Gezgin cruise missile. Once the Gezgin is fully integrated, the Reis class will gain a land-attack capability, allowing a submerged boat in the Mediterranean to strike targets deep inland. This evolution turns the Hızırreis from a simple hunter-killer into a strategic deterrent, capable of projecting power far beyond the coastline.
The journey to this handover has been a marathon of industrial perseverance. The project began under an agreement in the early 2010s, facing numerous delays caused by geopolitical friction, embargoes, and the sheer complexity of technology transfer. Yet, the acceleration of the timeline between the first and second boats is evident. While the lead vessel, Piri Reis, took years to navigate its trials, Hızırreis moved through its harbor and sea acceptance tests with notable speed following its launch in May 2023. By the time it was handed over in late 2025, the submarine had already completed deep-dive tests and system verifications, proving the maturity of the production line at Gölcük. TKMS officials at the ceremony emphasized that the program is now proceeding within cost and schedule envelopes, a critical assurance as four more sister ships are currently in various stages of construction.
Operationally, the Turkish Navy has wasted no time in integrating these assets into its “Blue Homeland” doctrine, a maritime strategy that views the surrounding seas as integral sovereign territory. Even before its formal commissioning, the Hızırreis was seen sailing in formation with the flagship amphibious assault ship TCG Anadolu and other surface combatants during the “Blue Homeland Guardians” parade in the Bosphorus. This public display illustrates the navy’s vision of combined arms warfare, where AIP submarines act as the stealthy tip of the spear, coordinating with surface fleets, drones, and coastal defense batteries. As the Reis class grows to its full strength of six vessels, it will provide continuous underwater coverage, ensuring that at any given moment, multiple silent hunters are patrolling the depths of the Eastern Mediterranean and the Black Sea.
Looking further ahead, the commissioning of Hızırreis is merely a stepping stone toward even greater ambitions. The knowledge gained from building the Reis class is already being poured into the MILDEN project, a fully indigenous national submarine program. Steel for the first MILDEN boat was cut in early 2025, signaling that Turkey intends to eventually move beyond foreign licensing entirely. Furthermore, the ecosystem is expanding to include the smaller STM500 mini-submarines for special operations and a fleet of unmanned underwater vehicles (UUVs) for reconnaissance and mine hunting. High-ranking officials have even hinted at a long-term goal of acquiring nuclear-powered submarines, positioning the current AIP fleet as the bridge between conventional roots and a nuclear future. For now, however, the TCG Hızırreis stands as the most advanced guardian of Turkish waters, a silent testament to a nation that has successfully transformed its naval industry into a powerhouse of the 21st century.
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