Mill Rock is a small unpopulated island between Manhattan and Queens in New York City. It lies about 1000ft off Manhattan's East 96th Street, south of Randalls and Wards Islands, where the East River and Harlem River converge.Mill Rock is located at Hell Gate, which was an infamously treacherous area for ships to pass.HistoryOriginally two smaller islands, William Hallet bought them from the local tribes in 1664. In 1701, John Marsh built a mill on one of them and the islands came to be called Great Mill Rock and Little Mill Rock. The island was later squatted on by Sandy Gibson, who operated a farm there.During the War of 1812, the War Department built a blockhouse with two cannons on Great Mill Rock. This fortification was part of a chain of blockhouses that was intended to defend New York Harbor and protect the passage into Long Island Sound against the British Navy.In 1885, the United States Army Corps of Engineers detonated 300,000 lb (136,000 kg) of explosives on adjoining Flood Rock; that island had been the most treacherous impediment to East River shipping. It was, most likely, the most forceful explosion in New York City's history at the time; it was felt as far away as Princeton, New Jersey. The explosion has been described as "the largest planned explosion before testing began for the atomic bomb", although the detonation at the Battle of Messines (1917) was larger. In 1890 the Flood Island remnants were used to fill the space between Great and Little Mill Rocks, producing Mill Rock.
