ONE night early this month, hundreds of yogis accustomed to grounding to the earth figuratively did so literally, on the green expanse of lawn near Pier 63 along the Hudson River. Schuyler Grant of the Kula Yoga Project, a founder of the event, Wanderlust Yoga in the City, made in situ additions to the yoga canon, suggesting, “Reach your heart to the water,” and encouraging participants to try handstands on the forgiving grass.

Traditionally practiced outdoors, yoga obviously is not a hothouse flower to be confined to a studio, yet for years urban yogis tended to relegate open-air practice to retreats in places like Bali or Mexico. That began to change in recent years, and while an exact timeline of the New York outdoor yoga movement is tough to pinpoint, one of the early pioneers was Dana Flynn of Laughing Lotus, who started holding classes in a West Village park in 1997, moving them to a rooftop in 1999.

“We brought the boom box and had Annie Lennox and Al Green blaring into the open sky,” Ms. Flynn wrote in an e-mail. She runs free weekly sunset classes for 80 students on Wednesdays in a park at 10th Avenue and 15th Street near the High Line, a series that began in 2009.