U Thant Island (officially Belmont Island) is a small artificial island or islet in the borough of Manhattan in New York City. The 100-by-200-foot (30 by 60 m) island, created during the construction of the Steinway Tunnel directly underneath, is the smallest island in Manhattan. Mean sea level in the East River is sometimes measured in reference to the “Belmont Island Datum”, 2.265 feet (0.69 m) below that of Sandy Hook.
In 1977, the island was adopted by a group called the Peace Meditation at the United Nations, employees at the United Nations headquarters and followers of the guru Sri Chinmoy, who served as the interfaith chaplain there. They leased the island from New York State, greened its surface, and unofficially renamed it after the Burmese former United Nations Secretary GeneralU Thant, a friend of Chinmoy. In 1982, Belmont Island was officially rededicated as U Thant Island. It is now the site of a metal “oneness arch”, preserving personal items of the island’s namesake.
The island is owned by the New York State Government and is currently protected as a sanctuary for migrating birds, including a small colony of double-crested cormorants. The cormorant population more than doubled from 2000 to 2011. The Borough, Block and Lot is Manhattan, Block 1373 (shared with Roosevelt Island), and Lot 200. Public access is prohibited. Since 2016, the island has been designated a Recognized Ecological Complex under the city’s Waterfront Revitalization Program. The reefs in the waters surrounding the island make it a popular spot for boats fishing for striped bass. The United States Coast Guard maintains a 57-foot (17 m) tall lighted beacon on the island, designated “Roosevelt Island Reef Light 17”; an earlier 23-foot (7 m) tall light had been erected in 1938, and another pair before then.
In the 1890s, William Steinway constructed the two tubes of the Steinway Tunnel for trolleys under the East River to link Manhattan to his also eponymous company town, Steinway Village, in Astoria, Queens. As part of that construction project, a shaft dug into the granite outcrop known as Man-o’-War Reef to reach the tunnels produced excess landfill that built up the reef and created a small island. Steinway died before his tunnels’ completion, and financier August Belmont Jr. finished the project in 1907. Belmont Island, named after the financier, became the legal name of the island. Four workers were killed in a 1906 shaft accident under the island. The tunnels, which pass directly beneath the island, are still used by the IRT Flushing Line (7 and <7>trains), and are now part of the New York City Subway system. Buildings from the tunnel stayed up until at least 1918.
