Di Ashley arrived in New York from Lancashire, England with a list of requisite tourist stops and sites to see. Her top priority: a boat tour of New York Harbor to get an up-close glimpse of the New York City Waterfalls art installation.

“I just wanted to have a look at the waterfalls and the tops of the buildings,” said Ashley, who paid $25 for an hour-long water taxi tour to view New York’s newest – and most temporary – wonder.

Ashley leaned over the side of the boat, taking in Lady Liberty and the Brooklyn Bridge. She admired the tallest of the four waterfalls, which was tucked beneath the bridge’s base.

“Magnificent!” she declared.

Biggest Since The Gates

Ashley was among the 86,000 tourists who visited the city this summer to view the four waterfalls, scattered around the harbor and created out of simple scaffolding, piping and pumps by Danish-Icelandic artist Olafur Eliasson.

The Waterfalls represent the city’s biggest public art project since 2005, when artists Christo and Jeanne-Claude shrouded Central Park in 7,503 saffron-colored flags. More than 700,000 people were said to have descended upon Central Park in the middle of winter for the Gates, generating an estimated $80 million in tourist spending.

The city also was ambitious in its vision for the Waterfalls, estimating the installation will pump out $55 million in revenue by the time the project comes down mid-October.

The Waterfalls installation already has attracted 340,000 viewers – about a quarter of them tourists, officials said. In the current troubled economy, the public art project has given the city’s hospitality industry a much-needed boost.

Hotel Helper

“We’ve had really good business for July and August,” said Karen Goldberg, director of marketing for Hotel Plaza Athénée, a boutique hotel on 64th Street and Madison Avenue. Goldberg said the buzz surrounding the Waterfalls, combined with the strength of the euro and pound, has drawn visitors from abroad.

More than 25 hotels throughout the city offered Waterfalls packages, combining lodging with a guided boat ride of the harbor, and sometimes a prix fix meal at a top-notch restaurant. The New York Hilton expects to have sold more than a hundred such tour packages by the time the exhibition ends.

“That’s certainly not as many packages booked as the Gates display, but definitely respectable numbers,” said Mark Ricci, a spokesman for the Hilton.

Liz Young, who runs a guided tour company and specializes in culinary-themed explorations of city neighborhoods, also cashed in this summer. Her “Dine, Walk and Float Tours,” a $125 excursion, includes a walk through lower Manhattan, a cruise on the harbor, and lunch at a downtown restaurant, such as Trinity Place in the Financial District.

Tree Trouble

“The Waterfalls tours have been wildly successful,” said Young. “I’ve had very positive reactions and a lot of repeat business because of them.”

But Young, who has run her touring company since 2003, recognizes the troubled waters locals know about.

The salt-water spray of the Waterfalls damaged trees along the Brooklyn waterfront and on Governors Island, spurring officials to cut the hours of the installation in those spots.

During the tour, Young delicately explains the damage and tells what’s being done to preserve the trees.

“It’s really such a shame because the artist is so interested in preserving the environment, “ Young said. “It’s kind of ironic.”