Close to 500 people participated in a flash mob in New York City’s Hudson River Park for Social Media Day.

The performance was the brainchild of tech startup Urthecast, which aims to provide the first-ever HD streaming video of the Earth from space. Surprised tourists waiting in line for Hudson River cruises were taken aback as the participants, clad in orange, ran to the boardwalk and started dancing.

“They were all volunteers,” said Jill Lennox, communications manager of the Urthecast, which helped organize the flash mob. “The Flash Mob of America coordinated it on Twitter and Meetup.com, and it spread by word of mouth.”

During the 11-minute dance, the performers formed themselves into several symbols, including the “@” sign, a hashtag and a heart, among others. The complete performance, which will include aerial footage from Urthecast, will be posted on their website on Thursday. A similar performance was held in San Francisco last April.

“The core of our platform is all about social media,” Lennox explained. “We’re doing a different twist on flash mobs — something you can’t fully see from the ground. That way, you can share it with friends and fully appreciate a different perspective.”