OVERVIEW: The S 21 *Santa Fe* [Balao Class] is a diesel-electric submarine operated by the Argentine Navy. Originally a United States Navy submarine transferred to Argentina, the *Santa Fe* represents a significant, albeit dated, component of the Argentine submarine force.

DETAILS: The *Santa Fe*'s origin lies in the Balao-class submarines constructed for the United States Navy during World War II. These submarines were designed for long-range patrols, anti-shipping warfare, and reconnaissance missions in the Pacific Theater. The Balao class incorporated improvements over the preceding Gato class, including a thicker pressure hull allowing for greater diving depths, and a more streamlined hull design for improved underwater performance. Many of these submarines were modernized during the Cold War era with updated sensors and equipment as part of the Greater Underwater Propulsion Power Program (GUPPY) conversions to extend their service life and increase their effectiveness against newer Soviet submarine designs. While the precise nature and extent of any GUPPY modifications to the *Santa Fe* prior to its transfer to Argentina requires further verification, the presence of specific US-origin sensors suggests some level of modernization occurred. The transfer of these submarines to allied nations like Argentina provided a cost-effective means of bolstering their naval capabilities and maintaining a degree of interoperability with US naval forces.

The primary role of the *Santa Fe* in Argentine service was likely focused on anti-submarine warfare (ASW) in the South Atlantic, as well as anti-surface warfare (ASuW) and maritime patrol. Given the regional geopolitical landscape, potential targets would have included surface combatants and submarines of neighboring countries. The submarine's diesel-electric propulsion system allowed for relatively quiet operation at low speeds, crucial for ASW missions. The *Santa Fe* could also be employed for intelligence gathering, surveillance, and reconnaissance (ISR) tasks, operating covertly near coastal areas or strategic chokepoints. While not specifically designed for anti-aircraft warfare (AAW), the submarine's inherent stealth allowed it to operate in areas with a potential air threat, albeit with limited self-defense capabilities against air attacks.

The S 21 *Santa Fe's* operational capabilities were defined by its sensor suite and weapons systems. The installation of the AN/BQS-4 sonar provided active detection capabilities, while the AN/BQR-2B offered passive listening capabilities to detect and classify distant targets. The AN/BQG-3 system was likely a passive ranging system, allowing for improved target localization. The SS 2A sonar's specific role is harder to determine without further data, but its inclusion likely contributed to a more comprehensive sonar picture. The submarine's periscope, both optical and electronic, served as vital tools for visual observation and target identification. The primary offensive capability resided in its 533mm torpedo tubes, capable of launching a variety of torpedoes optimized for anti-surface or anti-submarine warfare. The presence of a signal ejector suggests the capability to deploy countermeasures or communication devices.

SPECIFICATION: Length: 95.0 m || Beam: 8.3 m || Draft: 5.2 m || Disp: 1525 t

SENSORS: AN/BQS-4 || AN/BQG-3 || SS 2A || AN/BQR-2B || Generic Submarine Periscope, Optical

ARMAMENT: Signal Ejector || 533mm TT || 533mm TT