Jason Priestley, Sarah Jessica Parker and several other Hollywood stars went for a hike to help preserve the woods around historic Walden Pond.
More than 4,000 people registered for Sunday's second annual fund-raiser, including the project's founder, musician Don Henley, as well as actors Ed Begley Jr., Mary Stuart Masterson and Kevin Nealon and figure skater Paul Wylie.
The 6.2-mile trek was sponsored by The Walden Woods Project, founded in 1990 to preserve the forest where 19th century writer and conservationist Henry David Thoreau lived and worked.
In April, the project reached a deal to buy 18.6 acres near Walden Pond, blocking a proposed office park.
But with that purchase and some smaller ones, the project is more than $5 million in debt, organizers said. "The good news is we got it," Henley said. "The bad news is we have to pay for it."