The thickness of the outer crust is easy to visualize. It ranges from a few minutes walk to an hour at city street speeds. Nothing close to 12,000kms. "Under t

The thickness of the outer crust is easy to visualize. It ranges from a few minutes walk to an hour at city street speeds. Nothing close to 12,000kms. "Under the oceans (and Hawaiian Islands), it may be as little as 5 kilometers (3.1 miles) thick. Beneath the continents, the crust may be 30 to 70 kilometers (18.6 to 43.5 miles) thick."