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.

The Elephanta Caves are a collection of cave temples predominantly dedicated to the Hindu god Shiva, which have been designated a UNESCO World Heritage Site. They are on Elephanta Island, or Gharapuri, in Mumbai Harbour, 10 kilometres (6.2 mi) east of Mumbai in the Indian state of Mahārāshtra. The island, about 2 kilometres (1.2 mi) west of the Jawaharlal Nehru Port, consists of five Hindu caves, a few Buddhist stupa mounds that date back to the 2nd century BCE, and two Buddhist caves with water tanks.