Here's why:

* Continental Crust: This type of crust is thicker (around 30-50 km) and less dense than oceanic crust. It's made up primarily of granite and other less dense igneous rocks.

* Oceanic Crust: This type of crust is thinner (around 5-10 km) and denser than continental crust. It's composed mostly of basalt and gabbro.

Therefore, the thickest crust is found beneath the continents, which are the landmasses we live on.