INS Varsha

INS Varsha is an Indian Navy base at Rambilli, Andhra Pradesh, on the Bay of Bengal coast some 50 km south of Visakhapatnam, the seat of the Eastern Naval Command. It stands at the confluence of the Sarada and Varaha rivers. The installation is designated a Naval Operational Alternative Base (NOAB) and is built to support India's nuclear-powered submarine force. Personnel are drawn from the Indian Navy, while operational control of the base rests with the Strategic Forces Command in Delhi.

The base is configured to homeport Arihant-class ballistic missile submarines and nuclear attack submarines, with berthing under a network of underground pens cut into the Eastern Ghats to shield boats from satellite, aerial and air-attack threat. Water depth off the site permits submerged transit into the Bay of Bengal without surfacing. Pier construction also allows surface combatants to be accommodated, easing berthing pressure on the Eastern Fleet's dockyards at Visakhapatnam.

Supporting infrastructure includes nuclear engineering support facilities, crew accommodation, a VLF communication system, and a strategic technical area and command centre on forest land allocated in 2018. A Bhabha Atomic Research Centre nuclear marine and submarine missile research complex lies about 20 km away.

Planning began in 2005 under Project Varsha, which sought a submarine base within roughly 200 km of Visakhapatnam to relieve congestion at the port shared with the Ministry of Shipping; Gangavaram was examined before Rambilli was selected. Phase I began in 2011–12 with allocations for civil works and communications, and was completed in 2025, with commissioning set for 2026. Phase II, sanctioned in 2018, covers the command and technical area. The programme parallels Project Seabird at INS Kadamba on the western coast.