Khanderi is a fortified island 20 km off the coast of Mumbai. This along with its sister fort Underi formed the major fortification along the Mumbai coast. This was built by Shivaji in 1660 CE to keep a check on the Siddis at Murud-Janjira fort. However later on it lost its importance. Most of the fort is still intact the most prominent structure is a lighthouse built in 1837. It can only be accessed with the permission of the Bombay Port Trust.