For example, The Inca Trail to Machu Picchu can be a tough trek, and it takes a few casualties each year. But the real danger begins when you follow the trail past the mythical city and up Huayna Picchu, aka the “Hike of Death.” The old Inca staircase is carved out of granite and climbs about 1,000 feet in less than a mile. Plus, the route is full of rotting, crumbling rock, slippery stones, and exposed corners. Many people tackle the route totally unprepared—we’re talking flip-flops and no water.

Clouds and mist make the journey more difficult, and in some sections hikers must cling to old steel cables. Going up is the easy part. Coming down the steep slope often paralyzes travelers with fear. But it’s worth the pain—the view from Huayna Picchu on a sunny day is the best bird’s-eye view of Machu Picchu below.