West Coast Trail, Vancouver Island, Canada

Bears, wolves, and cougars call the woods around this trail home. Yet adventurers come from all over the world to hike the 48-mile route, which was built decades ago as a seaside trail to aid troubled ships that came in from the fickle Pacific waters offshore.

Mount Huashan Trail, China

With one mistake on the Mount Huashan trail, you will certainly fall to your death. This treacherous mountain trail, near Huayin, is used by wandering monks, Chinese students on vacation, and tourists alike. Ladders, cables, ledges, temples atop ridgelines, and impossible-looking staircases cut into rock define this unique and dangerous route.

Rover’s Run, Anchorage, AK

According to the Alaska Fish and Game department, a “few dozen” brown bears roam the area around Rover’s Run, a popular mountain-biking trail in the outskirts of Anchorage.

Devil’s Path, Catskills, NY

Said to be the toughest hiking trail in the East, this east-to-west voyage in the Catskill Mountains of New York traverses the spine of the mountain range an is just two hours north of Manhattan.

Peek-a-boo Gulch, Utah

Peek-a-boo Gulch is a slot canyon that cuts through sandstone bedrock as a narrow slit. Walls squeeze in on both sides. Hikers face interlinked potholes, tunnels, drops, fins of rock, and arches of stone silhouetted on blue sky.

Route up Pacaya Volcano, Guatemala

A trek uphill to see steam vents and rivers of lava on Guatemala’s Pacaya Volcano is a popular tourist hike, since it’s near Guatemala City. But after a shower of volcanic rock killed a reporter this spring, Pacaya National Park closed the trail.

Kokoda Track, Papua New Guinea

For various tragic reasons, four hikers died in separate incidents on the Kokoda Track during the 2009 trekking season. The trail runs for 60 extremely remote miles overland through Papua New Guinea’s Owen Stanley Mountain Range, climbing to more than 7,000 feet. A journey on the trail—which was the site of a World War II battle between Japanese and Australian forces—takes 4 to 10 days for most groups.

El Caminito del Rey, Spain

this cliffy route near Málaga has been closed for years. But it remains one of the world’s most famous dangerous paths. Built into the cliffs above a narrow river gorge in the district of Málaga, the El Caminito del Rey path was originally for hydroelectric power plant workers. It has three-foot-wide walkways hundreds of feet off the ground. Concrete sections have collapsed, leaving steel beams and rotting ledges exposed. Old cables bolted to the cliff provide some grip as trespassing hikers make their way along the route.