Precautions:

It's like walking to the edge of a deep pool. The metaphor is very cautious.

Idiom origin:

(1) The Book of Songs Xiaoya Xiaoya: Treading on thin ice with trepidation.

(2) The History of Emperor Guangwu in the Book of the Later Han Dynasty: You should tread on thin ice and approach the abyss carefully every day.

Related idioms:

Similarity: Walking on thin ice, approaching the deep valley, approaching the deep valley.

A bottomless chasm

Precautions:

Describe a deep place.