This, um, highly exclusive Upper Upper East side reef is for criminals only. Populated by 12,300 inmates and their officers, the island is barely 400 acres and serves as New York’s main jail complex. The prison has its namesake in Abraham Rycken, a Dutch Settler whose grand kiddies owned the island till 1884, when they sold it to the city and cashed in on $180,000—so, like, a studio in Bushwick. The only way you’re visiting here is getting yourself arrested, and then the boys in blue will give you a free ride over. [Photo via Wikipedia]

Hart Island is unoccupied - by the living. The island’s 101-acre potter’s field is home to the largest tax-funded cemetery in the world, with well over a million souls buried beneath it, a third of them infants and stillborn babies. Burials are conducted by Rikers inmates, and island access is thus restricted by the Department of Corrections . Those who can prove, through paperwork, that they are family members of the deceased, are only occasionally granted access to the island - and then they are allowed only to look at the burial field from a distance, from inside a gazebo. So not only can you not get to Hart Island, you shouldn’t want to be able to get to Hart Island. [Burials in the Common Trench at the Hart Island potter’s field. Photo via MCNY.]

The king of ruin porn and the wet dream of urban explorers, North Brother Island is an entire island of abandoned buildings. North Brother’s history begins in 1885 when Riverside Hospital relocated there from Roosevelt Island. An open minded smallpox hospital that also treated other life-threatening, quarantinable diseases, it was graced by such celebrity as Patient Zero: Typhoid Mary. It was the site of the 1904 General Slocum disaster, housed war veteran college students after World War II (AKA it’ll probably be NYU housing soon), and was a rehabilitation center for teenage drug addicts in the 50s. Today it’s a bird sanctuary, so you’ll need to pry a permit from the Parks Department or brave the East River’s currents with a boat or wetsuit to go exploring. Oh, and it’s right next to Riker’s Island, so security tends to be a little intense. [Photo]

It’s a freakin’ mussel-covered reef, but this list is all-inclusive goddammit. A 1995 New York Times article on New York’s islands writes for Middle Reef’s bio, “HISTORY none”. [Photo via Flickr/jag9889.]

These two are a real bummer. Apparently these islands were so impossibly useless neither Holland nor England could be bothered to fight for them. Hence the name. (Do we have to spell it out for you? No... nation.)Pretty sad. At high tide, both are completely submerged. [Photo via Marie Lorenz.]

Green Flats play peek-a-boo with the tide, so it’ll have to be pretty darn low for you to get a glimpse of these babies. “Flats” means shallow in nautical talk. The islands are green. Green Flats. Get it.

A part-time island, High Island houses the radio transmission towers for CBS Radio and is accessible from City Island via sandbar at uber low tide. It’s shaped like a gumdrop and used to be surrounded by sharks. Once, in 1967, a plane crashed into it, and no one listened to WCBS for a week. [Photo via Untapped Cities.]

Currently owned by a Mr. Alex Schibli of City Island, Rat Island has been, in past lives, a typhoid quarantine, an artists’ colony, and, according to the island’s surprisingly personal Wikipedia page, home to “a Great Blue Heron that sleeps on the island during daytime”. Legend has it the island was named for escaped prisoners of nearby Hart Island, known as “rats”, who’d swam to Rat Island before escaping to the mainland. [Photo by Nathan Kensinger.]

Unofficially named after former Burmese United Nations Secretary General U Thantt by a group of U.N. employees who followed Queens mystic Sri Chinmoy in the 1970s, Belmont Islandd is Manhattan’s smallest island. Just 100 by 200 feet, this spit of land is not open to the public, but that didn’t stop filmmaker Duke Riley from rowing a boat to it and proclaiming it a sovereign nation during the 2004 Republican National Convention. [Photo via 100thingsnyc.com.]

Only visible at low tide, the history and name origin of the Cuban Ledge are tightly linked and also blurred by time. Is the namesake the Cuban Lady, an ill fated cargo ship that ran aground on the island? Or perhaps simply a comment on the island’s similar shape to that of Cuba? Nobody can be sure. [Photo via Topoquest.]

Twin Island isn't an island (anymore), or even a twin, thanks to a 1934 landfill that connected East and West Islands (the “Twins”) to Pelham Bay. Twin Island is especially beautiful and important because its proof of legit nature (not just, like, grass) in the form of some of the city’s last remaining salt marshes. [Photo via Panoramio.]

1,000 feet from 96th Street, the seemingly inconsequential Mill Rock has housed many strange souls and events in its time. From 19th century farmer Sandy Gibson, who squatted and operated a farm on Mill Rock back when there were two islands - Great Mill Rock and Little Mill Rock - to the time the United States Army Corps of Engineers detonated the largest explosion New York had then seen to date, blowing up the treacherous Flood Rock with 300,000 lb of explosives (the remains of Flood Rock filled in Great and Little Mill Rocks to create the island there today). A Parks Department regulated three acre park on Mill Rock is not open to the public. Unless you are a bird. [The view of Mill Rock from the Wards Island Bridge. Photo via Wikimedia.]

All 89 acres of this Staten Island blip were once known as Dongan's Island, but over time people got confused and started calling it Duncan's Island, and then S.I. settler Arendt Jansen Prall Van Naardin, a local farmer whose name was longer than his land, purchased it. Guess why you can't come here? That’s right. The birds need their nature all to themselves. [Aerial view of Pralls Island off Staten Island in the Arthur Kill. Photo via Flickr.]

It’s not quite within Jersey’s state lines, but Shooters Island certainly deserves its own Springsteen song. Named for its days as a colonial hunting preserve, Shooters Island was a drop-off point for George Washington’s secrets during the Revolutionary War, was home to the Townsend-Downey Shipbuilding Company for 10 years at the beginning of the 20th century, and is now owned and controlled by birds. Unless you are a bird, plan to become one in the near future, or work for Audubon Society studying them, fat chance having a legal visit here. [Photo via Wikimedia.]

NYC is apparently trying to pay reparations to nature by giving all our unwanted islands to birds. Isle of Meadows is another no-humans-allowed bird sanctuary that narrowly escaped becoming a part of the Fresh Kills Landfill in the 1990s. Thank goodness, we always need more egret housing! [Photo via Freshkills Park, courtesy of the City of New York.]

Not to be confused with the raspberry candy treat, the Ruffle Bar is a tiny island that minds its own business in Jamaica Bay. It used to be a successful center for the clam and oyster business, but then the Department of Health decided it was too polluted for shellfish breeding. Today it is a lonely bird sanctuary. Sad little Ruffle Bar, why did we have to make her so dirty? [Photo via Marie Lorenz.]

A lot like Battery Park or Marble Hill, Hoffman Island is man-made because we were in the mood for some more land. The artificial island lives off Staten Island and was made from landfill in 1872. It was an immigrant quarantine station with a deeply depressing history (perhaps even more haunting than that of Hart Island), and currently serves as a massive waste of a potential public park. Instead, the Parks Service has given the place to the birds, and a few harbor seals who winter there - it’s a protected area. [Hoffman Island in the quarantine days of its youth. Photo via the Library of Congress.]

Hoffman Island's little sister, Swinburne is five acres smaller and a tad more remote than her twin artificial island. Also used as a quarantine for diseased immigrants, Swinburne’s history is nearly identical to Hoffman’s - both were also used as anchorages for anti-submarine nets, and are generally off limits to the public today. One difference, however, is that for whatever reason, while the buildings on Hoffman Island were leveled half a century ago, those on Swinburne still stand, although intensely decayed. [Photo via Untapped Cities.]

78 acres in the Long Island Sound with a history beginning in Native American habitation, then colonial farming, then military occupation and the construction of Fort Slocum, and now, abandonment. Currently uninhabited, the people of Westchester came together to reject a development proposal for luxury housing on the island back in 1981, but still haven’t decided what they do want to happen to the island. According to one news source, in the 45 years since Fort Slocum was shuttered, “Vandals, vagrants, Satan worshipers and pyromaniacs raided the unguarded island and set fires." [Removing ruins at Davids Island, including Building 44 (left) and Building 45 (the water tower, right).Photo via Hudson Valley Ruins.]

Perhaps the least boogie down part of the Bronx, City Island feels more like a small New England town than one of the five boroughs. This one and a half mile long island is populated by 4,362 sea-farin' folk who produce what’s probably the best (if not freshest) seafood in New York City. All the beaches are private, but the lobster’s great, and the Seaside Trolley will take you out there free of charge on the first Friday of the month. Many City Island residents take advantage of New York Harbor (unlike most mainland New Yorkers). [Photo by Nathan Kensinger]

Today it is a peninsula connected to Westchester, but before they filled in the water, Travers Island was an actual Island. Home to the tony New York Athletic Club, the island is chock full of top-notch athletic grounds, from an Olympic-sized saltwater pool to cabanas galore and facilities for tennis, yachting, rowing, croquet, and rugby. Membership costs $8,500, and there’s a dress code. Occasionally, though, epic fights apparently break out, so your call on joining. [“A crowd of spectators watch a track and field athlete jumping a stone-wall hurdle at Travers Island” (1896). Photo via MCNY.]

A 300 acre uninhabited oval in Jamaica Bay, Canarsie Pol is a part of Gateway National Recreation Area, and thus open to adventurous kayakers so long as they don't bother the birdies. A map from 1910 shows the island as being significantly smaller, suggesting that the island has expanded, likely due to sand and soil piling on Canarsie Pol after nearby waterways were dredged over time. Canarsie Pol is surrounded by other marshes, but none of them are considered large enough to be islands. [Photo via Outer Space Cities.]

Another former-island, Hunter Island is named for its former owner John Hunter a wealthy politician who built himself a wildly expensive Georgian style mansion and gardens on the island, as well as a bridge to the mainland (before fill was used to connect it to the Bronx). Today it is a part of NYC’s biggest park, Pelham Bay Park (it’s more than three times the size of Central Park), and is home to an oak forest and nature trail, as well as remnants of John Hunter’s gardens, from grape hyacinth to Tartarian honeysuckle. [An 1882 print of Hunters Island, via MCNY.]

Floatin' in the Long Island Sound, a part of the Hunter Island Marine Zoology and Geology Sanctuary, Cat Briars Island may not have much in the way of human history, but it compensates by bragging glacial erratics, ice aged boulders, and other natural things that don’t tend to last long when humans come along. [Photo via Empire Guides.]

Furman Island has since joined the Queens mainland, but you can still smell its history in Newtown Creek. Once a mecca of industrial activity, Furman Island was home to glue factories, bone burning plants, an “egg factory”, and generally a point of disposal for the 4,000 horses that used to annually die in Brooklyn. In 1910 Furman saw an end to its island status when landfill made obsolete the Shanty Creek waterway that separated it from Queens. [Photo via New York Shitty.]

Deep in the Rockaways, the A train defies the laws of gravity and soars above the tracks out across Jamaica Bay - just kidding, the A is actually just moving on track laid on top of Subway Island. Although built explicitly for elevating track, the 2010 bird census counted the city’s third largest glossy ibis collection there. Subway Island is vital to the allusion that the A train can walk on water. [Photo via New York Observer.]