Off historic Route 66 is this extinct volcano believed to be about 80,000 years old. Located in the midst of a plain that was once the bottom of a prehistoric sea, the crater measures about 1,508 feet in diameter - just over a quarter of a mile. Hikers can walk to the center of the crater via a breach in the surrounding walls. The breach was created by flowing lava but now makes a nice entry way into this pock-mark on the Earth's surface. Just like any desert trek, make sure you bring plenty of water and snacks, and a full tank of gas. Don't forget where you parked your car as the monotone landscape can confuse even the most level-headed people.