The depth of the Earth's crust compared to the rest of the Earth is comparable to the thickness of the skin of an apple compared to the entire apple.

Here's why:

* Earth's Crust: The crust is the outermost layer of the Earth, ranging from about 3-50 km (2-30 miles) thick.

* Earth's Mantle: The mantle is the layer beneath the crust, extending down to about 2,900 km (1,800 miles).

* Earth's Core: The core, both the outer and inner, is at the very center of the Earth, spanning about 3,486 km (2,166 miles) in radius.

Considering these sizes, the crust is incredibly thin compared to the mantle and core. The apple analogy is a good visual representation of this disparity.