At Huangshan.

I should explain the walkways on Huangshan. You don't walk up natural mountain trails. No, that would be too easy. They've built these "trails" of concrete stairs that are jammed right into the solid rock of the mountain. So rather than walk on soft earth, you are walking on concrete stairs 100% of the time. No wonder my knees hurt!

Some of these "stair trails" require that you go through narrow crevices. to continue climbing. This crevice was long, dark and spooky.