The Earth's crust is a relatively thin layer, varying in depth depending on whether it's oceanic or continental crust:

* Oceanic Crust: Ranges from 5 to 10 kilometers (3 to 6 miles) in depth.

* Continental Crust: Ranges from 30 to 70 kilometers (19 to 43 miles) in depth, with some areas reaching up to 80 kilometers (50 miles).

To summarize:

* Thinnest: Oceanic crust (5-10 km)

* Thickest: Continental crust (30-70 km, up to 80 km in some areas)