Why did you hike across Iceland?
I felt like a long walk. Plus, it's incredible to see the earth steaming in the lava fields at Namaskard and Krafla. It's like a thousand kettles that have been put on to boil.
What inspired you to take the first step?
For some of us, that compunction to climb Mount Kilimanjaro or travel with other pilgrims on El Camino de Santiago is deep-seated in our psyches. Wanting a real challenge and sense of accomplishment drives us.
Is wanderlust addictive?
As a boy, I used to look at the globe and want to see every inch, to get to all the corners and understand the different ways in which people live. In Iceland, for instance, they really believe in trolls. You can't possibly grasp the significance of their belief without going there.
Any essential gear for rugged journeys?
Comfortable boots and dry socks. Meindl's leather-and-Gore-Tex trekking shoes are just amazing. And I layer Bridgedale's Coolmax and Trekker socks to avoid blisters.
What do you carry with you?
Water—and the willpower to get going. That's all you need.
What do you bring back?
A rock or two. I can look at ones I picked up on a beach in Nunavut Territory above the Arctic Circle and be reminded of the entire trip: the colors, the patterns, and the whales in Lancaster Sound.
Who inspires you?
Wilfred Thesiger, a British visionary and a great traveler who lived an extraordinary life. He walked across Arabia's Empty Quarter. His Arabian Sands is sitting on my desk right now. That's my book; that's my man.
Is that why you went to Libya in April?
I wanted to see the real desert, so my wife, Martha, and I traveled to the Acacus Mountains to camp under the stars.
Where to next?
I'm thinking about Madagascar and Bhutan. The legs won't stop.
Level 1: Easy
Butterfield & Robinson offers an eight-day hike through the Land of Fire and Ice that starts and ends in the country's capital, Reykjavík. Highlights include a helicopter flight over the Askja volcano and Europe's largest ice cap, a midnight soak in geothermal pools, and an exploration of the Snaefellsnes Peninsula. The company also runs a family-friendly seven-day hike through the country's interior (www.butterfield.com; eight-day hike from $7,995 per person, double, all-inclusive).
It doesn't take long to traverse the world's smallest independent nation—occupying a mere 108.7 acres in the heart of Rome—but there's reason to linger: St. Peter's Basilica, where Michelangelo's most famous Pietà is found; the Sistine Chapel; and the halls of the Vatican museums. Pick up a map or book a private tour of the gardens at the on-site tourist office on the west side of the Piazza San Pietro (39-06/6988-2019; www.vatican.va).
Level 2: Moderate
This trip crosses the narrowest point of the peninsula, from the coast of the Andaman Sea to the Gulf of Thailand, through fishing villages, lagoons, and coconut plantations. As the crow flies, the distance is approximately seven miles, but expect to cover a few more on mountain passes. For a firsthand account of the journey taken by explorer Steve Van Beek, GPS coordinates, a printable map, and a local guide's recommendations, visit the newsroom of the Tourism Authority of Thailand on its Web site at www.tatnews.org/emagazine/2174.asp. Take note: there are no restaurants, public restrooms, or telephones along the way.
Level 3: Challenging
Fans of Alfred Wainwright can follow the 190-mile trek from the Irish Sea to the North Sea pioneered by the late author. The U.K.-based Northwestwalks (www.northwestwalks.co.uk) offers a 13-day hike on the full trail (from $1,773 per person), and two segmented hikes: an eight-day, 83-mile trek from Saint Bees Head to Kirkby Stephen, both within Cumbria (from $937), and a nine-day, 107-mile journey that picks up where the first hike leaves off, in Kirkby, and ends in Robin Hood's Bay in North Yorkshire (from $1,064).