Walking by the little organic food shop in her neighbourhood in Switzerland, Sarah Marquis noticed a photo in the window of the vast Mongolian steppe. Back at her home, the photo remained imprinted in her mind.
"I thought, where was that beautiful picture?" she recalled. "Then the research starts."
Looking at the map she saw how Mongolia connected to the Gobi Desert, Siberia and China. Her next adventure was born. For three years she travelled alone, walking and pulling her tent and food in a cart from Siberia to Australia, scrounging for water in the desert and surviving dengue fever alone in the Laos jungle.
It wasn't her first rodeo. At eight years old, she spent a night in a cave with her dog without telling anyone. At 17, she crossed central Turkey on horseback—with little riding experience. In 2002-03, over 17 months she walked 14,000 kilometres across the Australian outback; in 2006, she walked 7,000 kilometres through the Inca lands of Chile, Peru and Bolivia.
One consistent element of her adventures is her lack of any formal plan, just an organic process of embracing challenges as they arrive.
"I don't decide anything," she said about choosing her next adventure. "It's just one of those magical moments, sometimes just a picture."
One of her biggest challenges came when drunk Mongolian horsemen repeatedly visited her camp at night. To ward them off, she exploded in fury, behaving like a true crazy woman.
"I follow my instincts," she said. "It works out pretty well."
The encounter is just one of the memorable scenes described in her book Wild by Nature: From Siberia to Australia, Three Years Alone in the Wilderness on Foot. While humans can be potentially dangerous, she said, nature brings her comfort.
"You can read nature, you can't always read humans," she said, admitting she sometimes shows her animal side, sometimes her human side. Many humans, she added, have lost understanding of their role as a part of nature.
"My mission is to be the little bridge between nature and humans," Marquis said. "We can't survive without nature. We are nature. It's why I write books and go on expeditions. It's important to reconnect in any way possible, even if it's a lunch break in a park."
Embracing the challenges of self-propelled long-distance travel in natural areas is also a key element of Caroline Van Hemert's adventures, and her book, The Sun is a Compass: A 4,000-Mile Journey into the Alaskan Wilds.
An ornithologist and lifelong Alaskan, Van Hemert said the adventures she's embarked on with her husband, Pat Farrell, as partner, share common threads.
"One of the premises for us is that it's creative, interesting and challenging, something that pushes the edge of what's possible, wherever we're at physically," she said. "The human powered element is pretty important to me."
With her favourite landscape being where the mountains meet the ocean, their adventures have included travelling by skis and packraft across Alaska's Glacier Bay National Park from Yakutat to Haines, and a 6,400-kilometre six-month journey from Bellingham, Wash. to Kotzebue in the northwest Arctic, travelling by rowboat, skis, foot, packraft and canoe.
With her work as a government researcher being conservation oriented, she admits her wilderness adventures help her to connect to the species she studies.
"For me, it's about the experience of being out, with the freedom of not being encumbered by some of the things we're dealing with in our day-to-day lives," she explained. "The opportunity to get out and be reminded why I chose to study birds in the first place. It doesn't take very long being around other critters to realize they are much more impressive than we are. The element of seeing myself as a very small part of a much larger system is something that's really humbling, and really refreshing."
Now as parents of two boys, aged three and five, their adventures have evolved to family trips aboard their 32-foot sailboat, but with the same purpose.
"I want [my sons] to learn to look around and become competent being outdoors and in the wilderness," Van Hemert said. "I think that competence translates into so many other aspects of our lives. A place to find refuge when things are not going as we hoped. Those elements are so important for me, I hope I can share that with them."
For Britain's Kate Rawles, her adventures combine elements of personal experiences with efforts to raise awareness of Earth's biggest and most pressing environmental challenges.
In 2006, she cycled 7,300 kilometres from Texas to Alaska, using her bike as a "trojan horse" to converse with people about climate change along the way, a journey detailed in her book, The Carbon Cycle.
Since then, global awareness of how Earth's natural systems are being altered by human actions has increased, while the willingness for some governments to act hasn't.
"I followed the Rocky Mountains and wanted to see what I could learn about climate change in the belly of the oil beast," Rawles described. "At the time, it was the Bush administration—which looking back, seems pretty benign—but then he was the arch villain of the climate change drama."
For her more recent adventure and book-in-progress she's calling The Life Cycle, Rawles first took a five-day course to learn how to build her own bamboo bicycle. To lessen her carbon footprint, she travelled aboard a cargo ship to and from Britain to South America. Then she cycled 13,000 kilometres over 13 months from Colombia to Cape Horn.
"When you're cycling, you're really in the landscape," she said. "Especially if you turn up a woman on your own, and especially if you're on a bamboo bicycle."
Travelling by bike provides an unequalled opportunity to learn the value of trusting people, she said, as well as the realization how little "stuff" a person actually needs.
"I love how long-distance cycling tracks onto questions of sustainability," she said. "I really believe we can have a higher quality of life for all people with a vastly lower environmental impact."
While inspired by groups she met along the way working on "amazing" conservation-oriented projects, Rawles admits to being dismayed by how much of the world remains unconnected to nature.
"I find it really hard to wrap my head around the fact we haven't figured out how to live with the other species we share the planet with," she said.
And while the modern adventure community encourages people to get outside and experience nature, and places higher value on experiences over consumption, she said, it's also a community that encourages high levels of consumption through purchasing shiny new gear and travelling by airplane all over the world in pursuit of adventure.
"The adventure community has so much potential to help to preserve nature," Rawles said, "but also the potential to wreck it."