There was nowhere to go but up, unfortunately. I was standing on the Inca Trail, the legendary 43-kilometer trek that winds through the Peruvian Andes from the shores of the Urubamba River all the way to the ruins of Machu Picchu. A few of our guides run the roller-coaster route every year in under four hours. We were on the second afternoon of a journey that would take us four days.

My group of eight women friends was within sight of Dead Woman's Pass, which at almost 14,000 feet is the highest point of this centuries-old pilgrimage. It had poured through lunch, and I was sweating so much under my rain gear I could have sprouted a terrarium. The landscape had switched from a cloud forest rich with overhanging trees, wild begonias and bromeliads to open skies and puna, a grass that grows in ragged clumps. When I looked up, waterfalls spurted out of the sides of cliffs. Below, llamas grazed in the valley.

It was breathtaking, and like nothing I'd ever seen. Though my brain told me to stop and take it all in, I couldn't help thinking of what my friend, Wendy, announced five minutes after we first stepped onto the trail the day before.

"I hate hiking," she'd shouted to the group.

It was an interesting admission, given that the trip was her idea.

At this moment, I pretty much hated hiking, too. The altitude on the Inca Trail is daunting for someone who, like me, lives near sea level. But I'm also allergic to Diamox, a prescription medication that prevents mountain sickness. I'd heard stories of hikers throwing up, fainting and being so disoriented from oxygen deprivation that they raged at their companions. In extreme cases, it can be fatal.

Against a sky that looked as dense as a gray flannel blanket, I could see an opening between two mountains. It was certainly the pass, but I knew from checking my watch that it was at least an hour away. So I stuffed another wad of coca leaves — said to ease altitude-related symptoms — between my lip and gum.

And then I burned up the trail with only one goal in mind: get done. If Fredy, our wise and tenderhearted guide, had been anywhere near me, I'm sure he would have put his hand on my shoulder and cautioned me to slow down.

•••

The most extensive road system in pre-Columbian South America, the Inca Trail probably was built as both a transit network and pilgrimage to sacred mountain shrines. Today, hikers walk on the same stones the Incas laid. It's a mind-boggling display of human ingenuity and engineering, with paths made of stones fitted together like pieces of a 3-D puzzle.

The trail was made known to the western world in the early part of the 20th century, when American explorer Hiram Bingham and his team were studying Machu Picchu. Ever since then, this remote pocket of Peru has been a mainstay of those "100 Things to Do Before You Die" lists. And for good reason. Where else in the world can you experience jungle, snow-capped mountains and centuries-old ruins in a single afternoon?

For decades, the trail was crowded and strewn with trash. Porters, many of them native Quechua from villages surrounding Cuzco and the Sacred Valley, were treated abominably — paid rock bottom wages for labor that was literally backbreaking. It was so awful that Fredy quit guiding the trail because he couldn't stand to be part of such an abusive enterprise.

Today, the Peruvian government has taken steps to preserve this world treasure and improve the working conditions of those who make it possible for amateur hikers like my friends and me to enjoy it. Only 500 people are allowed onto the trail each day, and each group must travel with a guide who is licensed by the government. The Porter Law, which was passed in 2003 and is followed by ethical outfitters, sets strict weight limits and minimum wages.

We worked with Enigma, a locally owned adventure travel company that partners with agencies including Orient Express and Abercrombie & Kent. It was an experience that can only be described as glamp­ing — and then some. Sure we slept in sleeping bags, but you could hardly call being greeted with a celebratory pisco sour at the day's end roughing it. Our tents were always pitched by the time we arrived at the next campsite. Coffee was delivered first thing in the morning to our tents, as were warm bowls of water and bars of biodegradable soap.

•••

When everyone in our group made it to the top of Dead Woman's Pass, we raised our poles, posed for photos and cheered. It was covered in fog, so it was hard to make out any landmarks, including how the cliffs look like the profile of woman lying on her back. But the worst was over. It was time to enjoy the experience.

Or not. No more than 30 minutes into our descent, I felt like I was looking through glasses with the wrong prescription. I stumbled and fell on the stairs, now slippery with rain. When Wendy tried to distract me by pointing to some flowers, I could barely operate my camera.

When I arrived at the campsite, Fredy told me to go into my tent and rest. He assured me I'd be OK, but I was so nauseous that I couldn't imagine joining the others in the dining tent. When I told him there was a light band of pressure around my head, he waved to one of the porters to bring an oxygen mask.

The tears came when Fredy fitted the plastic mouthpiece around my mouth and nose. I knew this was my fault. I'd pushed myself when I should have respected the intensity of the trail. I'd been so proud that I was the third in our group to make it to the top of the pass. Now that decision struck me as just plain stupid. Suddenly, I felt like I was stranded in the middle of nowhere, years away from Machu Picchu, much less my home. It was raining hard enough that I could have yelled and no one would have heard me. "I miss my kids," I cried.

"You'll be fine by morning," Fredy assured me.

•••

Fredy was right. I unzipped my tent to discover that our campsite was perched on a ledge so high that I felt like I could see clear through the valleys to the Amazon.

When we set out after breakfast, I promised myself that I'd stay at the tail end of the group. And that's when the Inca Trail truly revealed herself to me. Angel's Trumpets in white, yellow and red dangled from branches like bells in a belfry. Hummingbirds buzzed past orchids the size of fingernails. Fredy talked to us about each flower, and often stopped to show us medicinal plants, including an acne cure that's popular with the teenagers in Cuzco. There was also something he called a "vagina plant," a concept that perplexed us until we asked him the next day to clarify what he meant. Turns out the Inca Trail has a plant that can cure yeast infections.

The Incas believed that many of the mountain peaks in this region were sacred, and it would be impossible to walk the trail and not feel in some way moved. One minute you are hugging the side of a mountain so as not to fall into the jungle below. The next you're squeezing through a cave. At one point the trail curved and suddenly we were standing high above the ruins of Sayacmarca, an elaborate archaeological site. It had taken three days to get there and was accessible only by foot. There was no ramp, no heliport, no shortcut. Like the original pilgrims, there were no rewards unless you did the work.

That evening we toasted the last night on the trail. We were eager to experience the majesty of the Sun Gate and Machu Picchu the next day.But I had no idea that before we set off Fredy would lead us in a prayer of thanks to mother earth that would cause me to weep with gratitude for two hours of our descent down thousands of feet of stairs.

Shooting stars drew white arcs against the black sky. We were huddled together in our down jackets, slap-happy with the rush of our adventure, guffawing at each other's jokes about the portable biffy and the vagina plant. We knew that the power of the group, not to mention the unwavering support of Fredy and his crew, had gotten us through this magical adventure.

I looked across at Wendy. "I thought you hated hiking," I said.

"I do," she answered. "But I love this." She gestured to the group, the sky and the smiles of pure love spreading across all our faces.

Elizabeth Foy Larsen, a Minneapolis-based writer, is the co-author of "Unbored: The Essential Field Guide to Serious Fun."