Drainage System of India: Which is the longest river entirely within India?

The Godavari River, stretching approximately 1,465 kilometers from its source in Maharashtra to its mouth in Andhra Pradesh, is the longest river that flows entirely within Indian territory. Often called the 'Dakshin Ganga' or 'Ganga of the South,' it originates from the Trimbakeshwar hills in the Western Ghats and drains into the Bay of Bengal, making it India's second-longest river overall after the Ganga-Brahmaputra system.