Mumbai Harbour, is a natural deep-water harbour in the southern portion of the Ulhas River estuary. The narrower, northern part of the estuary is called Thana Creek. The harbour opens to the Arabian Sea to the south. The historical island of Elephanta is one of the six islands that lie in the harbour.

Mumbai is the capital city of the Indian state of Maharashtra. Mumbai is the financial capital and the most populous city of India with an estimated population of 12.5 million (1.25 crore). Mumbai is the centre of the Mumbai Metropolitan Region, the sixth-most populous metropolitan area in the world with a population of over 23 million living within the Mumbai Metropolitan Region. Mumbai lies on the Konkan coast on the west coast of India and has a deep natural harbour. In 2008, Mumbai was named an alpha world city. Mumbai has the highest number of billionaires out of any city in India as well as in Asia.