The Indian Navy is making significant strides in enhancing its submarine capabilities by equipping Kalvari-class submarines with Air Independent Propulsion (AIP) technology. The Defense Research and Development Organisation (DRDO) and Larsen & Toubro (L&T) are collaborating to develop and install the AIP system, with the first major refit expected for INS Kalvari by September 2025. This technology breakthrough aims to reduce vulnerability to detection, increase underwater endurance, and enhance operational mobility for the Indian Navy. The integration of AIP technology into the Indian Navy's fleet is crucial for effectively monitoring the growing naval presence of adversaries like China and Pakistan in the Indian Ocean Region. While concerns about operational readiness during upgrades exist, the indigenous development of AIP showcases India's advancement in naval capabilities. Additionally, Project-75I seeks to further strengthen India's combat prowess by acquiring submarines with Fuel Cell Air-Independent Propulsion technology, offering extended underwater stealth capabilities. Navantia's Bioethanol Stealth Technology (BEST) system, utilizing bioethanol to generate hydrogen onboard, presents a unique proposition for India's submarine acquisition programs. The competition between contenders like MDL-TKMS and L&T-Navantia reflects the strategic importance of AIP technology in modern naval operations. As India continues to evolve its submarine fleet with advanced propulsion systems, the AIP technology stands out as a game-changer in ensuring maritime security and combat readiness in the region.