The Nankoweap Trail is not for the faint of heart. There are steep drops reaching hundreds of feet, and the trail is very high. It’s the most treacherous and difficult trail in the Grand Canyon National Park. Trekkers get 11 miles of exposure to the sun and heat, which is why it’s so dangerous. Cell phones don’t work on the trail, and GPS signal is often blocked by precipitous cliffs, so if you’re in trouble, you won’t be able to reach anyone. This doesn’t sound like a trail we’d voluntarily go on. Additionally, the trail is not marked, so you’ll have to be an expert trail finder in order to safely and successfully walk this trail (Travel Channel).