WILSON, N.C. (AP) – Hiking hundreds of miles didn't used to excite Trevor Thomas, a thrill-seeker who skied, mountain biked and raced Porsche sports cars.

But when he went blind in 2006, the winding nature trails that once seemed pedestrian posed new challenges – even a sense of danger.

“In my sighted life, I was an adrenaline junkie,” Thomas said. “I thought that it was a dull sport – not what I was used to. But then I discovered ultra-distance hiking, and it was the ultimate adrenaline rush because really, it's surviving.”

Thomas and his guide dog, a 2-year-old Labrador retriever named Tennille, are walking on a backcountry tour of North Carolina on the famed Mountains-to-Sea Trail.

The Charlotte resident began his Tar Heel trek April 6 in the Smoky Mountains. He and Tennille had hiked 664.6 miles of the nearly 1,000-mile trail Tuesday afternoon, when he stopped to camp for the night at Terry Creamer's home outside Sims.

“I like to shock the sighted world,” Thomas said. “I choose to do the things that 99.9 percent of the population can't fathom doing or don't know that they have the ability to do.”

Thomas hopes his trek will help him raise $5 million for Guide Dogs for the Blind, the California nonprofit that gave him Tennille, who he calls “the best hiking partner I've ever had.”

“They gave me a dog I could never afford,” he said. “I figured if I could raise some money for them, I could help another person get a dog.”

Thomas was in law school when doctors diagnosed him with atypical central serious chorioretinopathy, a condition he described as his autoimmune system attacking and destroying his macula.

“I went from just thinking I might need some glasses after law school to eight months later, I'm blind,” he said. “It was quite a shock to the system.”

Thomas said he has limited ability to see shapes in well-lit settings.

“I don't have any visual acuity, but I feel fortunate in the blind world,” he said. “Everything is like a charcoal color. When it gets dark or when it's really cloudy, everything is black.”

In 2008, Thomas became the first blind hiker to complete a solo trek of the Appalachian Trail. He's hiked through the Smokies, conquered California's John Muir Trail and trudged up steep mountain paths in Colorado.

“I keep pushing myself,” he said. “I want to do things not in the handicapped world. I want to do things basically just like everybody else.”

Today, the support of 17 sponsors allows Thomas to complete ultra-distance hikes year-round. Thorlo, a Statesville-based manufacturer of high-performance athletic and comfort socks, is underwriting his Mountains-to-Sea Trail hike.

Thomas has averaged about 16 miles per day, logging 18.1 miles on Wednesday. He starts early and walks much of the day's distance in the morning so his California-bred black Lab doesn't tire in the hot sun.

“We started in the snow,” he said. “We had rain the first 45 days. After we got done with the rain and the cold, then we went to the scorching heat.”

Tennille has boots and a heat-reflective shirt, along with cooling towels and gel beads that Thomas can press to her neck when she's panting in the late-spring sun.

Navigating is a challenge, especially through detours and poorly marked sections of the trail. Tennille's been trained to spot trail markers and help guide Thomas. He also receives direction from his iPhone, which is equipped with a talking maps feature.

“It's not as easy as you'd think walking down the side of the road – especially for the two of us,” Thomas said.’

For sustenance, Thomas munches on protein bars, nuts and jerky. When he enters a new town, he makes a beeline for the nearest greasy spoon diner or roadside grill and washes his hamburgers down with an ice-cold Coca-Cola.

Thomas is on a 5,000-calorie daily diet, down from the 10,000 calories he consumed each day while hiking through the mountains.

“It's the perfect diet plan,” he said. “I can eat anything and everything I want, and I'm guaranteed to lose weight.”

Thomas and Tennille are hiking the trail by themselves, but “trail angels” – individual and family sponsors – and film crews working for the various sporting goods brands who underwrite his adventures have joined him for stretches of the trail.

Along the way, Thomas and his four-legged trail guide have experienced their share of Southern hospitality. Supporters will bring Thomas a Coke or stop to offer encouragement and help.