Underi (also called Jaidurg) is a fortified island near the mouth of Mumbai harbour south of Prong's Lighthouse. It is a companion fort to Khanderi and currently lies in Raigad district, Maharashtra. These islands of Khanderi and Underi served as one of the landmarks for ships entering Mumbai harbour.[1] Underi is smaller than Khanderi.
The fortification was built by Kahim of the Siddis[2] in 1680 CE. [3]
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