Barr Trail, Pikes Peak, CO
Credit: Steve Krull / Getty Images

Legendary mountaineer Bred Barr forged this legendary trail through Pike's Peak virtually on his own, and the result is glorious: an 11.8 mile journey ending in a summit that offers incredible views from 14,0000 feet. Besides the physical hazards of scrambling up 7,900 vertical feet, and the likelihood of altitude sickness, unpredictable weather is a serious hindrance, especially in summer when lightning storms are extremely regular and dangerous – about half of the nearly 50 reported lightning strikes in Colorado since 2000 have involved hikers and campers – and heavy hail or extreme temperature drops can be perilous. [barrtrail.net]