BRITISH TRAVEL WRITER ALASTAIR HUMPHREYS has cycled around the world, rowed across the Atlantic, and trekked 1,000 miles through the Empty Quarter of the Arabian Peninsula. But his acclaimed 2014 book, Microadventures: Local Discoveries For Great Escapes, celebrates exploration and adventure closer to his London home. “A microadventure has the spirit (and therefore the benefits) of a big adventure,” he writes. “It’s just all condensed.” Why would Coloradans, who live within a few hours’ drive of world-class hiking, skiing, cycling, camping, and white-water paddling, want to abridge their adventures? Well, I-70 traffic, for one. Plus, microadventures are inexpensive, quick, and often family-friendly. They’re good for the environment—many destinations can be reached easily by light rail or bus—and they’re good for you, too. Adventure is “a state of mind, a spirit…