A Thread of Sky is a narrow rock crevice on the Xiangshan Nature Trail, reached by a 30- to 40-minute hike from the Xiangshan trail entrance. Passing through the one-person-wide rock passage opens views of Taipei 101, Xinyi District, and the surrounding greenery. The passage is narrow enough that you have to step aside for people coming the other way, and the floor and walls are wet, so watch your head. There is no lighting at night, so a phone flashlight is needed.