Nobody portrayed last year’s Outside Festival as a test event to see if the concept — promoting Colorado’s $17-billion outdoor industry by attracting thousands of outdoors enthusiasts to Civic Center for fun, films and iconic speakers — but that’s essentially what it was. Organizers believed it would work, but nobody could be sure.

It passed the test. It drew 18,000 attendees, 20% of whom traveled from out out of state, with an estimated economic impact of $16 million. So its organizers — outdoors media giant Outside Interactive Inc., in partnership Visit Denver and the Outdoor Recreation Industry Office of state government — feel even more confident about this year’s event which is set to run Thursday through next Sunday.

Outdoor companies didn’t know what to expect a year ago, Outside chief executive Robin Thurston conceded.

“It was the first year, and people were kind of gauging how many (attendees) were going to be here,” Thurston said. “This year they know a lot of people are going to be here, so they’re investing more. Last year was a test. We didn’t really know. I think the formula really worked.

“This year,” he added, “we actually get to see in full form what that formula is going to do.”

As was the case last year, there will be booths and activities in Civic Center Park, along with a film festival. Speakers will include big wall climber Alex Honnold, magician and “endurance artist” David Blaine, long-distance swimmer Diana Nyad and high-altitude mountaineer Melissa Arnot Reid, the first American woman to climb Mount Everest without supplemental oxygen.

Films, curated in partnership with Mountainfilm, will include Girl Climber, a documentary on Boulder native Emily Harrington’s quest to make free-climbing history on El Capitan in Yosemite National Park, and Remaining Native, the story of native American runner Ku Stevens, which was shown last month at South by Southwest.

A variety of ticket packages are available on the event website.

New this year: Outside Ignite, an outdoors version of Shark Tank for outdoors entrepreneurs, with the winning pitch receiving $100,000 in start-up prize money. There also will be musical entertainment. This year’s artists will include Khruangbin, Lord Huron, Sylvan Esso and Waxahatchee.