Mauna Kea access road, USA -
Conquering the Mauna Kea access road means following a 22-km (14 mi) mostly paved route that meanders up Mauna Kea, a dormant volcano on Hawaii's Big Island. The road tops out at 4,200 m (13,781 ft), and in fact Mauna Kea is one of the few places in the world where you can drive from sea level to 4,267 m (14,000 ft) in about two hours.