EAST RIVER — Most New Yorkers have probably never heard of U Thant Island — but it’s likely many have spotted the tiny outcropping of rocks in the East River near the United Nations or at least have traveled underneath it.
It was created from land dug up for the East River tunnel that the 7 Train now rumbles through and was named for Thant, a former UN secretary general, where a “peace arch” was erected in his honor and time capsule buried in the 1970s with the former leaders’ speeches.
This obscure little land mass — not accessible to the public — was the first of several islands within city limits that authors Sharon Seitz and Stuart Miller discussed on a recent evening boat tour organized by Open House New York, the nonprofit celebrating its 10th year of programs providing access to the architectural and historic gems that are often hidden or off-limits.
As the sold-out tour aboard the "Zephyr" glided up the East River, Seitz and Miller, shared stories from their book, “The Other Islands of New York City” — now in its third edition — which discusses the history of more than 40 islands in the area.
“We thought if we’re native New Yorkers and we don’t know that much [about these islands], there are probably a lot of people who don’t know about them,” Seitz said about why the duo wrote the book’s first run 20 years ago.
Before the naming of U Thant Island, for example, it was called Belmont Island, the authors explained.
William Steinway, of the famed Astoria piano family, had begun the tunnel project from Queens to Midtown in the 1890s for his trolley line but passed away before it was finished.
The tunnel was completed in 1907 by August Belmont Jr.
The tour looked at the city’s history of using many of these outlying pieces of land for institutions, such as hospitals, jails and asylums to warehouse the sick, criminal and indigent.
They were on Blackwell’s Island (now Roosevelt), then Wards and Randall’s islands, Rikers and North Brother Island, the now-vacant green space between the Bronx and Rikers Island where the infamous “Typhoid Mary” spent 30 years in confinement.
“By 1820, New York passed Philadelphia in population,” Miller said, noting that much of the growth was attributed to new immigrants. “The city looked to the islands to get rid of people.”
Some islands, like Rikers, are, of course, still used for these purposes.
As the tour passed the city’s jail complex, the authors explained how the island grew from one facility on some 80 acres in the 1930s to nearly a dozen buildings on 415 acres, plagued by a troubled history of overcrowding that sometimes resulted in violent uprisings, such as one in 1990 when 130 guards and inmates were injured.
The nearby North Brother Island, which was vacant until the city moved a hospital there in 1885 from Blackwell’s Island, became infamous as the place where bodies washed ashore in the 1904 wreck of the General Slocum steamship, which killed more than 1,000 people. An unfinished hospital for tuberculosis was later used to house World War II veterans, and the island later housed a facility for juvenile drug addicts from the 1950s through the early 1960s.
No longer open to the public, North Brother Island had become a bird sanctuary for herons and egrets, but recently the birds have abandoned their nesting grounds there — though there are many wading birds on the neighboring, smaller South Brother Island, the duo noted.
Seitz and Miller wrote their first edition before the city and real estate developers began thinking differently about the waterfront and making big changes to some islands, like Roosevelt Island, where the old small pox hospital — a remnant of the institutional past — sits on the southern end next to where the Franklin Delano Roosevelt Four Freedoms Park is slated to open in October.
It’s also not far from where the outdated Goldwater Hospital will be replaced by a state-of-the-art eco-friendly $2 billion Cornell NYC Tech campus. A far cry from the insane asylum there that reporter Nellie Bly went undercover to write about in the late 1800s, the tech campus is expected to attract the best and brightest future start-up founders.
“The islands are an ever-changing story,” Miller said, “and reflect the city’s priorities at the time.”