Payoff Everything is concentrated when you make a one-day double crossing of the Grand Canyon, like I did in May. Your fuel: GU and 5-Hour Energy offset the 20,000 calories you’ll burn—and keep your pack light. Your attention: Tiny scorpions come out at night, blunting the fatigue that could send you stumbling off a cliff. And most of all, your adventure: The physical challenge is highly satisfying, and so is the scale, but the real reward is covering so much ground that you sear every ecosystem and geological wonder onto your mental hard drive. —Jonathan Dorn
Do it The vaunted rim-to-rim-to-rim, or r2r2r, is a burly 44 miles and 22,000 feet round-trip via the South and North Kaibab Trails. Alternatively, return via the Bright Angel Trail—it adds three miles, but cuts 500 feet of climbing and offers water and shade options (the South Kaibab doesn’t). Don’t attempt the r2r2r in hot weather. Go in April (more water in side creeks) or October (heat fades).
Don’t try a mega-trip like this one until you’ve notched a 25-miler—feeling strong—in the weeks prior. On game day, here’s how to stay hydrated and energized:
» Drink every 15 minutes. Carry a three-liter bladder, and refill at all sources. Eat about 200 calories (for women) to 250 calories (for men) per hour; bring 4,000 calories total, with a mix of sweet and salty—the latter important for replenishing sodium.
» Wear a wide-brimmed hat and light-colored clothing that covers most skin. Use SPF 30 sunscreen (see page 49).
» Start at first light. If you feel signs of heat exhaustion—nausea, clamminess, dizziness, lethargy—rest in the shade, drink, eat, and consider turning back.
RESOURCES Getting there Free shuttle buses run frequently from the park’s hotels, campgrounds, and parking areas to all trailheads on the South Rim. Map Trails Illustrated Grand Canyon #207 ($12; natgeomaps.com). Contact (928) 638-7888; nps.gov/grca
See Two More
The 32-mile Pemi Loop from Lincoln Woods Trailhead on New Hampshire’s Kancamagus Highway tops 10 4,000-foot peaks. (603) 466-2721; outdoors.org
Circumnavigate Oregon’s Mt. Hood on the 41-mile Timberline Trail. Trail runners do it in 10 hours. (503) 668-1700; fs.fed.us/r6/mthood