The Ubehebe Crater is situated in the north of the Valley and it's quite a drive to get there. But if you plan to see Scotty's Castle then Ubehebe is only 8 miles away from the castle. The crater was formed by a massive vulcanic steam explosion a few thousand years ago. There is a trail to the bottom of the cone.
Ubehebe Crater is thought to be the result of a relatively recent cryptovolcanic eruption. It formed probably a few thousand years ago when magma rose close to the earths surface and caused ground water to flash into steam. It must have been quite an explosion as the crater is 2,000 feet across and 750 feet deep. It's possible to hike down into the crater.
There was a great smattering of plantlife along the trail into the crater. That was a great surprise! No matter where one goes, life persists...