This weekend, several hundred New Yorkers will perform a feat that many have imagined but few have completed. They will walk the entire perimeter of Manhattan Island, rain or shine.

Dubbed “The Great Saunter,” the 32-mile journey is the year’s big event for the nonprofit walking group Shorewalkers. Organizers expect about 500 people to participate in this year’s 20th-annual event. As Shorewalkers’ founder, Cy Adler, pointed out, “the best way to see New York island is at 3 miles per hour.”

The ramble is not a race. The quickest finishers take just under eight hours, with most strolling it between 11 and 13 hours. Last year, a group straggled in at 1:30 a.m.

Saunterers meet near the South Street Seaport at 7:30 a.m. and reconvene at the seaport’s Heartland Brewery at the end of the day. In between, they walk through approximately 20 shoreline parks, including Riverbank State Park, Inwood Park, the Harlem River Esplanade, Highbridge Park, and Carl Schurz Park.

Event organizer Walt Wright says his favorite area is the West Side stretch between Riverbank and Inwood parks. At Inwood, where the group stops for lunch, “I swear there are places where you can’t see any signs of humans,” he said. “It must look like it did hundreds of years ago.”

“What I would advise anyone,” he added, “is that West Side is really a lot prettier than the East Side.”

Just as living in Manhattan can be a blend of bliss and frustration, there are annoyances along the way for saunterers. At the top of the island, the group must walk along the Henry Hudson Parkway for a mile or so, and they walk on city streets for a few dozen Midtown blocks. Mr. Wright said that north of 127th Street, there are lovely little green spaces with benches that have been fenced off for years, reason unknown. The group used to have to ask permission from the Trump Organization to traverse the West Side rim above 69th Street, where Donald Trump owns a row of apartments. The Hudson River Park now cuts between the apartments and the river, providing public access to the shoreline.

Mr. Adler, the author of “Walking Manhattan’s Rim: The Great Saunter” (Green Eagle Press), said that the first Saunter was considerably more difficult than it is today. “At that time, the shoreline was a mess,” he said. It was an obstacle course of fences, crumbling piers, and unsafe areas. “There was really no good way of doing it, but we did.”

Mr. Wright agreed that Manahattan’s perimeter parks are in much better shape than they were 20 years ago. “The coastline is changing,” he said, “really for the better.”

Even the most enthusiastic strollers may be exhausted by end of their journey. Although there are no steep hills to scale, Mr. Wright said some participants have complained that “it’s harder than a marathon.” At 26.2 miles, marathons cover less distance. And since they’re not typically run at a leisurely pace, they require far less time on one’s feet.

Those who want to join in the fun but are daunted by the prospect of tackling the whole island need not stay home. They can drop in at any one of five meeting places along the way. Of last year’s hundreds of participants, Mr. Wright said that 175 received certificates for tracing the whole perimeter.

At the very least, Mr. Adler said, “No one should die without having walked the Henry Hudson Bridge and the George Washington Bridge.”

Saturday, 7:30 a.m., meet near the South Street Seaport at Fulton and South streets, $15. Please see www.shorewalkers.org for more information and a full list of meeting places.

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