Next time you head out for a hike, either close your eyes tightly or wrap a bandana around your head and eyes and see how far you can make it down the trail without straying or falling down.

Then imagine doing that for 2,650 miles. Trevor Thomas, a blind hiker, hopes to cover that distance on the Pacific Crest Trail before the autumn snows pike up.

While many of us were rushing our taxes out the door last week, Mr. Thomas and two companions was setting north on the PCT, the latest journey he's embarked on both to measure himself and to raise awareness about blindness in the world. He also, no doubt, is an inspiration to many who have lost all, or much, of their sight and wonder if life can ever be the same.

An adventure junkie for most of his life, Mr. Thomas gorged himself on adventure sports. Before going blind he was into extreme skiing, parachuting, mountain biking, climbing, and racing Porsches. Then a little more than five years ago his sight was taken, almost overnight, by an auto-immune disease, "a typical central serous chorioretinopathy."

"Basically what it is is something in my body decided that my maculas were a foreign agent, and my immune system attacked it and killed it, so it cost me my sight," the 41-year-old said earlier this month before heading to the trailhead at Campo, California, with the Mojave Desert awaiting.

"The way I equate it, losing your sight later in life, was kind of like being in the prime of your life and having to go back to kindergarten. You have to learn everything all over again, from reading and writing to using a computer all the way down to how to navigate around the streets and matching your clothes, things that most people would never think about," he said.

Most people, confronted with blindness, might not think about long-distance hiking. But Mr. Thomas, after receiving encouragement from another sightless athlete, Erik Weihenmayer, readily took to it. Working himself into shape with hikes that slowly grew to 100 miles, then 200 miles, and 300 miles in length, he headed north from Springer Mountain, Georgia, in the spring of 2008 hoping to complete a thru-hike on the Appalachian National Scenic Trail by fall.

“Originally, I started on the AT to prove things to myself. The way I went blind, it wasn’t like one day I woke up and I couldn’t see. It just degenerated over a period of about six months," recalled Mr. Thomas. "And as my sight got worse and worse and worse, my world got smaller and smaller and smaller. After I got introduced to hiking, I wanted to prove to myself that my world wasn’t small, and looked to hiking and said I need to find probably the longest trail that I can get to that’s on the East Coast.

"The gear outfitter that I went to had just gotten off the Appalachian Trail, and while I was buying some gear from him, he wouldn’t stop telling me these amazing stories," he continued. "So I decided, when I was in the outdoor outfitter, I said if I can do that, then I’ll be able to do anything else in life.”

At the time no other blind hiker had gone unassisted end-to-end on the 2,175-mile AT, according to Mr. Thomas' research. Daunting though the trek might have seemed, he soon found a comfort zone while hiking north to Maine. And along the way, he found different rewards than those more commonly enjoyed by those who can see the trail in front of their feet. While he could smell the coniferous and hardwood forests and meadows around him, feel the rain on his face, the hot sun on his back, hear the rushing streams beneath the footbridges he crossed, he couldn't see these things or frame a photo to hang on a wall or fill an album.

"When I was sighted, of course, I would summit a mountain simply for the spectacular views in addition to the shear accomplishment of doing it. Like most sighted people. They want to, they get to the top of the mountain and the first thing they want to do is, 'Hey, I want a snapshot of this, look at the serene environment I’m in,'" Mr. Thomas said. "I view the accomplishment of getting to the top of any mountain without sight, I view it as a greater accomplishment for me because it’s a little bit harder. So when I get to the top of a mountain I experience, as opposed to taking pictures for a keepsake that I can look back on, one thing I do is I take a rock. So I have my individual summits, I guess I would say tactilely.

"If I feel a rock, and all rocks are different, I can think back, OK, this is the mountain I did when I’m feeling this rock," he explained. "And then when I’m on top of the mountain, I use my other senses, other than my eyes. I think of the smells, I think is it a windy day, do I feel the sun on my face, or is it cloudy and possibly raining? So any other sense, other than sight, is how I take in an individual summit.”

With his sight gone, Mr. Thomas quickly discovered that his other senses were sharpened by his increased reliance on them. Through his sense of hearing he can tell if he's in a forest or on moving across a bald in the Smokies or a granite slab in New England. His feet also grew incredibly sensitive.

"I learned on the trail that the feeling in the bottom of my feet has become incredibly acute. I can literally, with so many miles on my feet, through my shoes, and through my soles, I can actually feel something as small as the paint line on a road," he said. "The way I navigated up the AT is I felt as if I was on the trail through my feet. Things like that have become much, much more acute.”

While hiking the AT, Mr. Thomas would try to reach a trail shelter each night, because if he could do that he could find water in the streams often located nearby. If not he would just camp where he ended up. While he grew adept at navigating the trail through the feeling in his feet and with the aid of two hiking poles, there were times when he felt lost, such as when the trail would cross barren rock.

"I had quite a bit of trouble to be honest with you on those. When I wasn’t lucky enough to bump into a cairn, or if it was say one of the sections that wasn’t worn -- a lot of the AT that goes over the granite, the granite balds, there are so many hikers who have been on it, you can feel the little divot that is the AT -- so sometimes I could follow that," he said. "If I really, really got stuck and I didn’t know where I was, I simply, I just stopped and I waited. I waited for anybody to come by on certain sections. And a lot of hikers that I was with, they knew I wanted to hike alone, I would have people that would go ahead of me, and there were some people who would stay behind me. If the people ahead of me got to a section that they thought was maybe a little bit too confusing for me, they’d stop and wait. They’d help me through whatever that section would be. If I got into a section where I was really concerned that I was lost, I would stop and maybe somebody from behind would catch up with me and then we’d go through."

Most folks plan on thru-hiking the AT in five-and-a-half or six months. Mr. Thomas, after his initial struggles, quickly found his pace and finished in "exactly six months and two days."

“My pace when I started as pathetically slow to be honest with you," he said. "But as I put in more miles and put in more miles and more miles, I got, actually got very, very quick, and my pace now is, I would say as fast as it was, maybe a little bit faster than it was when I was sighted."

His pace will need to be good if he's to reach the northern end of the PCT by November. While his AT trek was done unaccompanied, outside of the hikers he'd meet on the trail, the Pacific Crest trek will be approached with two companions.

"There are so many people who start to do the AT, it was a much easier environment for me, and it’s not as rough a trail as the Pacific Crest, so until I got up to the northern terminus on the AT, there were almost always people that you would run into," Mr. Thomas explained. "The PCT, I actually put together a team. We call ourselves Team Farsight. My two teammates that I’m taking with me, I’m doing simply for safety in numbers, because I’ve been told that you start the PCT alone, you’re going to end it alone. And going across a glacial moraine for a blind person would not be the smartest thing to do by yourself.

"But my teammates in no way, shape or form, unless it’s positively necessary, are going to give me any assistance. I want to pretty much do it as purist as humanly possible for someone in my condition.”

Mr. Thomas has picked up a number of sponsors to help him underwrite his trek. There's hiking boot manufacturer Ahnu, clothing and gear companies such as Marmot and Columbia, pack companies such as Granite Gear and Osprey, and, of course, GPS manufacturer Garmin. While there currently doesn't exist, according to Mr. Thomas, a GPS unit that can guide a blind hiker along corridors as narrow as the AT and PCT, he plans to test some new generations of the devices to see how far they've come.

"At this point technology with GPS, for a blind person, inaccuracy in even 5 to 19 meters is an eternity," he said. "One thing that my team and I are doing, one of my sponsors is Garmin, we’re going to be testing out the exact accuracy of the unit to see if it could be adapted to somebody who is visually impaired.”

Such a device could improve immensely helpful next year, when Mr. Thomas hopes to conquer the Continental Divide Trail, the most challenging of the country's three premier long-distance trails because it hasn't been fully blazed.

Another sponsor is spot, the personal safety beacon that can be triggered to alert friends and family back home that you're safe on the trail. This device also allows you to link to Google Earth and show your friends where exactly you are. On his way north Mr. Thomas plans to utilize this so you can follow his travels.

While Mr. Weihenmayer has summited Mount Everest, Mr. Thomas has no designs on climbing to the roof of the world.

"We actually have an agreement. He can climb high, and I’ll trek far," Mr. Thomas said with a laugh. "He’s climbed everything, so I would be the second guy to climb Denali or whatever. He’s sticking to the mountains and I’m sticking to the trails.”