Go ahead and type “world’s deadliest hike” into a Google search. You will get HuaShan (Mountain Hua). This is an image of the famous cliffside plank walk on the South Peak. The plank walk itself isn’t very long, but it is a 2,000 foot drop if you slip. Harnesses are mandatory and can be rented onsite.
The scary part for many is that it is a two-way path meaning that as you go others will need to pass. At times you will be required to crawl around other people. Getting to the plank walk takes hours and is challenging, even if you take one of the cableways. The West Peak is easier, but the North is worth doing (you will need time and endurance). It can be a multi-day experience if you hike up from the base of the mountain.
The mountain itself can be a challenge to get too. It is located about 75 miles outside of Xian, which is fairly easy to traverse with the new bullet trains, but once you get to Huayin (the city at the base of the mountain), it can be difficult to find anyone who speaks anything other than Chinese. We even had trouble communicating with the people who worked there.
If you do decided to go, be prepared to spend a lot of money. You will need to anticipate spending money for the train, the entrance ticket, the bus to the cableways, the cableways, the harnesses, food, water, and room and board. It is all rather pricy especially for this part of the world, but the experience is worth it.