ne morning last week, Zoe Klein, a 24-year-old circus performer from Brooklyn, stood practicing her act, which involved swinging a pair of tethered balls, and stared out to the Hudson River.

"Growing up in New York, I always felt boxed in," she said. "I always knew we were surrounded by water, but it always felt dirty or inaccessible."

Actually it was not too long ago that the stretch of waterfront where she was standing was dirty and inaccessible. But it has been recently reclaimed as part of the Hudson River Park project, a lengthy effort to upgrade the West Side riverfront and install miles of landscaped public space and freshly paved pathways for runners, bikers and skaters.

Although traffic was heavy on the nearby West Side Highway, Ms. Klein said she considered the spot on the western fringe of Greenwich Village an oasis of serenity. "I come here all the time, to counteract the stress of living in the city," she said.

Things are changing along New York's waterways and waterfront, and Ms. Klein is not the only one noticing. City residents are now zealously embracing the waterfront.

Yoga groups convene on a Hudson River promenade just south of West 72nd Street on what was once a fallow railyard. Fishermen are casting for schools of striped bass off the Battery. And the Downtown Boathouse offers free kayaking programs.

"New York is a water city — we're the Venice of the East Coast — but for a good part of the 1900's, the city turned its back on the waterfront," said John Waldman, the senior scientist with the Hudson River Foundation. "Now we're turning around and discovering it."

Cleaner waters have encouraged many revitalization projects along the city's 578 miles of shoreline. Despite economic hard times, waterfront development projects are proliferating from Staten Island to the Bronx.

"The development of the waterfront is one of the Bloomberg administration's most critical economic and neighborhood priorities," said Daniel L. Doctoroff, the deputy mayor for economic development and rebuilding. "With maritime industry uses gone or fading, we can reclaim parts of the shoreline. We have a once-in-a-century opportunity to reclaim New York City's waterfront, so we're seeing a lot of things beginning to come together."

In Manhattan, progress is being made on the $400 million Hudson River Park park project to reclaim five miles of ramshackle waterfront from Battery Park City to 59th Street. There are also plans to revitalize the Harlem Piers, renovate Fulton Street and create a "Champs-Élysées"-style promenade on West Street.

In Queens, the Queens West project has two residential towers up and another planned, and there are proposals to create new access to Jamaica Bay and the Flushing River waterfront. The city hopes to create a waterfront Olympic Village for 2012 in Long Island City.

In Brooklyn, plans to develop 1.3 miles around the Manhattan and Brooklyn Bridges into commercial and recreation space are on tap, as is a revitalization project for a 1.6-mile stretch of industrial waterfront in Greenpoint and Williamsburg.

In the Bronx, there are plans to redevelop the waterfront near Yankee Stadium and the Bronx River. In Staten Island, city officials hope to redevelop the former Homeport Navy site, and a new pier at South Beach is almost complete.

Four of New York City's five boroughs are part of an urban archipelago. This was one of the big draws for the Dutch, who built wharves in southern Manhattan in the 1600's. As commercialism began to grow, waterfront structures began blocking views and access. And the less-than-savory sailors and dock hands made the waterfront synonymous with mob activity, prostitution and crime.

So New Yorkers avoided the water, wrote Luc Sante in "Low Life," his book on New York's underbelly. Mr. Sante noted that Fifth Avenue became the most desirable residential address because it was farthest away from the Hudson and the East River.

Early in the 20th century, highways were built blocking the shoreline, which was thick with freighters and ocean liners. The fishing industry declined as the waters became more polluted. Foul water also meant the end of Whitehall rowboats off the Battery and grand boathouses and swim clubs with staircases descending into the water.

"For generations, the river was considered an unpleasant place to go," said the city's parks commissioner, Adrian Benepe. "It was where you put slaughterhouses and where poor kids went to swim."

By midcentury, manufacturing began to decline and many piers became inactive. Still, the city's nautical life was reduced to tiny pockets, like Broad Channel and City Island.

But the federal 1972 Clean Water Act and better sewage treatment practices improved water quality. Starting in the 1980's, industrial waterfront stretches began to be redeveloped into residential or recreational areas, including Battery Park City and Chelsea Piers.

The once dying ferry industry has recently been revived. Developers and city officials continue to see new opportunity in the old wharfs and dilapidated shoreline buildings.

So New York is finally shaking off a legacy of the padlocked waterfront, and undergoing a "mindset change," said Raymond Gastil, author of "Beyond the Edge: New York's New Waterfront" (Princeton Architectural Press, 2002).

"The idea that you can go kayaking off a pier in downtown Manhattan is a pretty bold expectation," he said, "but one that is being realized."

Carter Craft, program director of the Metropolitan Waterfront Alliance, a division of the Municipal Art Society that advocates for more public access to the shoreline and more water transit, said that the "change in New Yorkers' consciousness" certainly helps economic revitalization. But he said that waterfront parks should do more than just lead people to the water. "There are still relatively few ways for Manhattan Islanders to actually interact with the water," he said. "The current park designs are not as boater-friendly as they should be. The waterfront should not be an edge, but rather a gateway."

Even as a work in progress, the transformation of the waterfront is something the city is pretty proud of. The Parks Department is planning an opening ceremony later this month for an interim bike path around the perimeter of Manhattan.

"Opening the waterfront for recreational use in the 21st Century is as important at the creation of Central Park, Prospect Park and Riverside Park in the 19th Century," said Mr. Benepe of the Parks Department.

Last week, Jose Gerald, 65, a retired merchant seaman from Carroll Gardens, was fishing off the Valentino Pier in Red Hook

Mr. Gerald, who moved here from Puerto Rico, has been fishing at this spot for 45 years, looking for blackfish, blues, porgies and striped bass.

"Forty years ago, the water was filthy," he said. "Now it's beautiful. Before nobody wanted to eat the fish. Now everybody wants to eat the fish. Now you even see some kids swimming over here some times. I don't know the name, but the fishing ducks are back."

The same day, a man sat on the waterfront in upper Manhattan with no fishing pole, but rather a bottle of beer in his hand.

The man, a pay phone repairman named Robert K. Morton, sat at a table set outside at the Tubby Hook Cafe at Dyckman Street and the Hudson River. The cafe offers spectacular views of the river, of the George Washington Bridge and the Palisade cliffs.

"When you sit out here, you don't think you're in Washington Heights," Mr. Morton said, squeezing a lime into his beer. "I work for the phone company and I get to go all over. It doesn't get any better than this."