Trevor Thomas was stuck near Avalanche Gulch in the shadow of Mount Yale. The trail had been erased by the winter’s avalanches. The reroute of the technical Collegiate Loop Trail around the debris field did not match his directions.

“I had absolutely no idea where to go. I said to Lulu, ‘I don’t know what to do here,’” said Thomas, who lost his vision 13 years ago. “And she chose the way and we got back on track.”

Earlier this week Thomas and Lulu, his golden Lab guide dog, completed the 160-mile Collegiate Loop, climbing and descending more than 50,000 vertical-feet for 13 days as they circled seven fourteeners in the Sawatch Range.

“Two days shorter than I planned,” said Thomas, who started hiking more than 13 years ago, shortly after he went completely blind.

Trevor Thomas navigates the Collegiate Loop Trail with his guide dog, Lulu. The route is challenging in good years, but this year, there was the added challenge of snow and the aftermath of avalanches that scoured away the trail. (Photo courtesy Trevor Thomas)

Thomas can’t see the singletrack. Or the signs. Or the cairns. Lulu handles the seeing stuff.

“It’s a symbiotic relationship. I consider myself the big picture guy and she’s my detail girl,” he said Wednesday from his home in North Carolina, two days after notching his historic loop around the Sawatch. “I rely on her judgment to keep me safe.”

Thomas, who goes by “Zero/Zero,” is the world’s only blind, sponsored through-hiker. Since 2008, when he through-hiked the 2,175-mile Appalachian Trail solo and unassisted, he has become an internationally acclaimed trail boss.

Using a finely tuned sense of hearing and memorization of detailed trail data to navigate, Thomas has ticked off all the biggies, becoming the first blind person to solo through-hike the Pacific Crest Trail, the John Muir Trail, the Long Trail, the Tahoe Rim Trail, the Mountains-to-Sea Trail, the Colorado Trail and thousands of miles of lesser-known routes.

Thomas’ trail accomplishments mirror the mountain feats of Colorado’s own Erik Weihenmayer, whose inspirational ascent of Mount Everest and kayaking descent of the Grand Canyon have fueled Weihenmayer’s call to live a “No Barriers” life.

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Thomas was age 36 and barely two weeks into completely losing his sight in 2005 when a friend insisted he go hear Weihenmeyer give a talk in Charlotte, North Carolina, about his climb up Everest.

“From the pits of my depression, this friend dragged me to hear a blind man speak. It turned out to be Erik and he was the first blind person I’d met,” he said. “He was doing all the stuff I used to do before I went blind.”

Erik Weihenmayer

He met with Weihenmayer after the presentation.

“He told me, ‘Don’t let society decide what we can or can’t do.’ That made a difference for me,” said Thomas, who raced cars, jumped from airplanes and skied in the backcountry before losing his vision. “I give a lot of credit to Erik for starting me on this path.”

The Collegiate Loop was Lulu’s first big trip; her debut as Thomas’ trail guide since the retirement of Tennille, the Labrador who delivered Thomas his first real dose of independence on the trail.

He used to hike with partners, but they were under strict instructions to help him only if he was in imminent danger. He didn’t like using partners as anything other than emergency back-ups. In 2011, he tried the Colorado Trail — solo and unaided — and made it 125 miles when he had to bail. It wasn’t working.

He came home and started calling schools who breed and train guide dogs for the blind, asking for a dog that could help him hike alone for weeks through remote backcountry. That did not go over well.

“I called nearly every guide dog school in the country and they all said ‘Guide dogs can’t do those things.’ A couple even told me blind people shouldn’t either,” he said.

Guide Dogs for the Blind in California wasn’t able to train a dog to help Thomas hike through the mountains, but they liked his idea and were able to train him on how dogs learn.

He spent months training Tennille, working every day. In 2013, six months to the day he got her, they set out on the nearly 1,000-mile Mountains-to-Sea Trail in North Carolina.

“No partner. No guide. No GPS. Just us,” he said. “I found on that trail true independence. There was nobody on the trail. I was the only person to complete the MST that year.”

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Thomas and Tennille kept at it for years, notching all sorts of first-ever, solo, blind-hiker records as they traversed more than 10,000 miles of trails. In 2015, he and Tennille finished the 500-mile Colorado Trail, marking the first solo trek by a blind person and the first by a guide dog. (They also climbed Mount Elbert on that trip, marking yet another pair of first-ever records for the duo.)

“Just us versus nature,” he said.

But guide dogs carry heavy workloads and they get weary. A year-and-a-half ago, Tennille was on Arkansas’ Ozark Highlands Trail with Thomas when she let him know she was ready to retire.

“She said I’ve done my job and I’ve had enough through-hiking,” he said. “So, it was painful, but I let her retire. And I called the school again, hoping for a second miracle.”

They had just had a litter. All the pups had names starting with H. (Aside: Apparently guide dogs are named like hurricanes. And their alphabetically assigned names are checked against national databases to make sure each pup has an exclusive ID.)

Thomas spent nine months training Honolulu, a span in which he dropped the “Hono” from her name. He was hoping it would be easier considering his time training Tennille. No such luck.

“Every dog is different. They have different responses to stimuli. Different abilities. Different personalities,” he said. “It was really exciting training a new dog to have similar skills, but I had to use different techniques.”

The extra training time helped because Lulu didn’t get a chance to dabble in through-hiking. After only a few three-night test hikes in the Appalachians, she stepped onto one of the most challenging mountain treks in the country.

“Taking her to 10,000 feet and then trying to explain to her how long this is going to last, that was fun. It was hard to explain to her, and I knew she had concerns,” Thomas said. “She had her reservations when we were out there, but the cool thing is that she knew she was going to do it because that’s what I asked her to do. It’s just pure devotion.”

Paul and Nancy Lukacovic helped arrange food resupply drops on Thomas’ route. The Aurora couple — who spent more than a decade training guide dogs — also organized check-ins on Lulu during the hike, making sure she was staying healthy.

They had volunteered to help Thomas on his previous Colorado Trail hikes with Tennille. Paul Lukacovic said Thomas is an exceptional dog handler and trainer who has developed his own techniques for teaching his dogs to address his very particular needs. Where some might need their guide dog to find, say, bananas in a grocery store, Thomas asks his guide dog to locate things like cairns, singletrack, trail signs, campsites, water sources and more.

“He’s learned how to enhance the dog’s training through repetition and saying this is what I’m expecting now,” Lukacovic said. “He’s a very good dog handler and that makes me feel better about the dog, too. It’s a partnership, and it’s not all him. The dog has to do what he’s asking.”

Trevor Thomas stops for a photo with his guide dog, Lulu, earlier this month on the Collegiate Loop Trail. (Photo courtesy Trevor Thomas)

The Collegiate Loop was a big test for Lulu, Lukacovic said. Tennille was always eager on the trail.

“Tennille just ate it up. She’d get the pack on and it was all business,” he said. “I think Trevor is still trying to figure out just how much Lulu enjoyed this trip. I wonder if it might take a little bit more time for Lulu to reach the phase where Tennille was.”

Lukacovic, who helps script detailed trail descriptions for Thomas, marvels at the hiker’s dedication and perseverance on the trail.

“It’s a reminder that you set your own limitations and don’t let other people tell you what you can or can’t do,” he said.

Thomas memorizes trail details and keeps notes on his phone. He tracks both his cadence and time in his head, so he knows where he is on the trail. When a trail intersection or stream crossing or other navigational challenge is coming up, he can alert Lulu to be on the lookout. She wears a harness, which is connected to a 6-foot stretch of climbing rope that Thomas holds. Lulu’s subtle movements translate to that rope and Thomas is fluent in her guiding language that travels through that leash.

They started at Twin Lakes and took the East Loop first, heading south. Thomas had done that section before with Tennille. The West Loop, which follows the Continental Divide Trail on the other side of the Sawatch, is notoriously challenging, with long stretches of rock fields and this year, snow. The West Loop was even more tricky this year after the winter’s trail-scouring avalanche cycle.

Lots of debris. So much rock. Landslides. Snowfields.

“The trail would just arbitrarily disappear and reappear,” Thomas said. “She is pretty much making her decisions as we go. She is providing me the visual information I can’t get myself.”

Hikers take pretty good care of the Continental Divide Trail. Cairns mark the spots where scree or snow can hide the trail.

“I can’t see those. But fortunately my dog can,” said Thomas, who listens for Lulu’s footfalls and tries to place his boot in that exact spot. “Lulu would find them for me, but it didn’t feel like there was a trail there at all. Pardon the pun but we were blindly picking our way through the rock fields.”

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