South India lies in the peninsular Deccan Plateau and is bounded by the Arabian Sea in the west, the Indian Ocean in the south and the Bay of Bengal in the east. The geography of the region is diverse, encompassing two mountain ranges, the Western and Eastern Ghats, and a plateau heartland. The Godavari, Krishna, Tungabhadra, Kaveri, and Vaigai rivers are important non-perennial sources of water. Bengaluru, Chennai and Hyderabad are the largest and most industrialised cities in the region. Chennai is termed as Gateway of South India, being one of the largest metropolitan cities in India.