The Shorewalkers walking club also sponsors walks along New York’s “interior shores,” such as Meadow Lake in Flushing Meadows Corona Park in Queens. (Lea Winerman/For The Washington Post)

“No New Yorker should die without walking over the George Washington Bridge,” says Cy Adler. That’s a grand pronouncement, but Adler, 84, can speak with some authority. As the founder of the nearly 30-year-old walking club Shorewalkers, he has logged many hundreds of hours traversing New York’s shorelines and bridges — and the George Washington is his favorite.

Manhattan may be an island, but standing on its busy streets, it can be difficult even for residents to remember that the city is ringed by more than 500 miles of riverside cliffs, beaches, urban parks and waterfront industrial zones.

New York City’s shorelines: Where to go, what to do, where to stay, where to eat

Adler knows those shores better than most. The native New Yorker started Shorewalkers in the early 1980s. Over the decades, the group — whose motto is “see New York at three miles per hour” — has grown into a not-for-profit organization that advocates preserving and increasing public access to the region’s shores.

The group’s many volunteers lead several walks every week, year-round, throughout the five boroughs and the New York suburbs. Most of the walkers are locals, and the walks aren’t exactly tours — they don’t come with a running history of the area. But the volunteers do lead walkers on off-the-beaten-path treks through areas that visitors would be unlikely to find on their own.

For example, the George Washington Bridge, which stretches from Upper Manhattan at 178th Street to the Palisades, the 400-foot cliffs that line the New Jersey side of the Hudson River. I’ve driven over this bridge many dozens of times on my way to visit family and friends in New York, but I’d never known that it was walkable.

One October weekend, I learn that Adler is leading a walk across the bridge, so on a chilly but sunny morning, I take the subway to meet him and six other walkers at the 178th Street bus terminal, just a few blocks from the bridge’s entrance. A freak snowstorm dumped a couple of inches of icy slush on the city the night before, but Adler is undaunted. So are my fellow walkers, a diverse group of experienced shorewalkers and newbies ranging in age from their 20s to their 50s. I’m the only out-of-towner.

“I do this for the exercise, and I see parts of the city I’ve never seen before,” says social worker Suzy Sanford, a native New Yorker who discovered the Shorewalkers last year and has been walking with them regularly since.

We’re supposed to head across the bridge and then continue several miles north along a trail at the foot of the Palisades. The walk starts out promisingly — the sun is warming up the sidewalk and melting last night’s slush. But at the bridge, we find our way blocked. The gates to the pedestrian walkway are closed; apparently the city has decided that it’s too icy to be safe. We’re disappointed, but Adler regroups and tells us that he’ll lead us instead on a walk around the parks of northern Manhattan and into the Bronx.

We head north through the Washington Heights neighborhood and into Fort Tryon and Inwood Hill parks, surprising patches of greenery at the island’s very northern tip. Walking along Inwood Hill Park’s quiet forested paths, it’s hard to believe that we’re just a 15-minute walk from the subway. When the path parallels the river, it offers gorgeous views of the Palisades and the Hudson as far north as the Tappan Zee Bridge, 20 miles away.

At one point, we cross over a busy rail line that carries Amtrak trains into the city. Adler says that in the 1980s, he and other shorewalkers used to walk along this then-abandoned former freight line that hugs the Hudson shore. Since Amtrak took it over, he says, that’s no longer safe. That’s just one of the changes Adler has seen in the three decades he has been hiking New York’s shores.

“It used to be a lot more porous,” he tells us. But the new restrictions are balanced by improvements in more official means of access, including miles of new parks and paths. It’s now possible, for example, to walk or bike along an uninterrupted greenway that traverses nearly all of Manhattan’s West Side waterfront, from Battery Park in the south to Dyckman Street in the north.

And in March, Mayor Michael Bloomberg announced a $3.3 billion plan to invest in revamping even more of the city’s shorelines.

Adler appreciates the new parks, but his slightly buck-the-rules spirit remains. As we round the tip of Manhattan, we come to the Henry Hudson Bridge, which leads to the Bronx. Once again, though, the pedestrian access ramp is blocked, this time by a bright orange “Work Zone, No Access” sign. Adler considers it for a moment, then says, “It’s Sunday, no one’s working.” We continue over the bridge without incident and wander through Riverdale, a leafy, suburban-feeling section of the Bronx, before heading back to Manhattan.

Three weeks later — after my blisters have healed — I return to New York ready for another walk, this time along an “interior shore” of sorts: three lakes in Kissena and Flushing Meadows Corona parks in Queens. Walk leader Rachel Donner, a retired librarian and teacher, starts our trek with a quote from F. Scott Fitzgerald’s “The Great Gatsby” that evokes the area’s not-so-illustrious past as a cinder dump: “a fantastic farm where ashes grow like wheat into ridges and hills and grotesque gardens.”

The park is more pleasant these days, with two lakes ringed by reeds and acres of playing fields. And although it’s not as beautiful as the northern Manhattan walk, it’s equally interesting. Flushing Meadows was the site of the 1939 and 1964 World’s Fairs, and our route winds us past some iconic remnants of those events — a giant steel globe and the skeleton of the New York State pavilion, where teenagers now skateboard nearby.

In Kissena Park next door, we walk past another lake, New York’s only velodrome and a huge and thriving community garden where the signs, catering to the local populace, are mostly in Chinese. More than six miles later, we emerge hungry and tired onto Main Street in Flushing, Queens — the center of one of New York’s largest Chinatowns — where Donner leads us to her favorite dim sum restaurant for a restorative late lunch.

It seems like the perfect end to a New York weekend, but before I leave, I have one more task. This time, I decide, I’m going to make it over the George Washington Bridge. So the next morning I take the subway back to 178th street and, happily, find the pedestrian pathway open for business.

It is, as Adler promised, a wonderful walk. Standing in the middle of the nearly mile-long span, I can see the skyscrapers of Midtown Manhattan in the distance, dwarfed by the expanse of the river and the rocky Palisades. It’s a beautiful sight, and although I’m sure that the next time I see it will be at 60 mph, I’m glad that I took the time to look at three mph this once.

New York City’s shorelines: Where to go, what to do, where to stay, where to eat

Winerman is a freelance writer in Alexandria.