A daunting stretch of whitewater bisects a 3,700-square-mile wilderness of never-before-skied peaks. You’ll need two rafts, five handles of liquor, and a gun for bears. It’s not the Yukon, Siberia, or Tibet. It’s Idaho. And it takes serious planning to pull off. This is what happens when you let a kid with a pet badger handle the details. By Frederick Reimers.