Last summer, hikers with bizarre backpacks could be seen trekking the trails in the Garden of the Gods, climbing stairs at Red Rocks Amphitheatre and peering at the gorillas in the Denver Zoo. Now we know why.

Google Maps sent the wanderers to places where no Google Street View car has gone before. On Tuesday, more than 30 virtual off-street tours of Colorado hiking trails and tourist attractions go live online, with much of the physical work done by employees of Visit Denver and Visit Estes Park, the city visitor bureaus.

“Imagery has come to be an expectation for people,” said Susan Cadrecha, communication manager for Google Maps. “It’s part of our overall mission to be more comprehensive.”

Google’s Street View maps, which rolled out around 2007, let people remotely see what it’s like to walk down actual streets. Using cameras atop cars to capture a 360-degree view of driving down the street, Google’s process takes those images and stitches them together so people online are immersed in a scene. They can turn left, right or look behind to see what one would see if driving down the street.

But in places where cars aren’t allowed, Google started its Trekker Loan Program in 2012. The Grand Canyon was one of the first locations to get a street-view tour. There, the Google Maps team snapped 9,500 images of the national park to map out 75 miles of hikes, according to a 2013 story by Wired magazine.

Google, which has a large office in Boulder, wanted to do something in Colorado, Cadrecha said. Last summer, it reached out to local visitor agencies. While Google’s own team handled the Flatirons, volunteers from Estes Park and Denver visitor bureaus did the hikes using “the Trekker.”

Enclosed in a round case, the 360-degree camera is perched atop the Trekker backpack — as if a giant-headed space alien is piggybacking on the hiker’s back.

“We had two people on site at all times, one with the pack and the other person letting people ahead know what was happening and that there was a person with this weird-looking pack coming,” said Brooke Burnham, director of marketing and communications for Visit Estes Park. “We didn’t want anyone to be concerned about it but excited.”

Google’s software automatically blurs out faces and certain words, including some of the signage at the Denver Zoo. In all, 32 off-street locations in Colorado were added Tuesday to Google Maps.

The new virtual venues are a very familiar, although less exhausting, experience. You won’t be out of breath when climbing the stairs at Red Rocks. But you can’t just virtually zip up to the top. You climb the stairs one chunk at a time.

Visit Denver submitted about 20 locations to Google, which were whittled to 10. Places that didn’t make the cut? Sports stadiums.

“(Google) felt that there were a lot more restrictions on public access even though we included some places that are ticketed,” said Justin Bresler, Visit Denver’s vice president of marketing. “Most of the tracking was done outside. But at the Botanic Gardens, we did go inside the conservatory.”

Bresler did some of the Denver tours himself. He traded off with friends or other staffers when the 60-pound pack proved too weighty.

“We had a lot of good stares and questions from people,” said Bresler, who carried a pack around Red Rocks, City Park and the Wild Animal Sanctuary in Keenesburg. “And we had to wait for a rattlesnake sunning itself on the path at Red Rocks.”

The snake didn’t make the cut, and Bresler said he didn’t hide any Easter Eggs in the footage, although you might find “my son in the background,” he said.

Ultimately, he said, his team did it for the opportunity to give potential visitors another way to research the city.

Besides, he said, “Because the equipment was free and it was just staff time, we felt the investment was minimal.”

Where did the Trekker Loan Program go?

Flatirons:

Denver:

Estes Park:

Rocky Mountain National Park:

Colorado Springs:

Tamara Chuang: tchuang@denverpost.com or visit dpo.st/tamara