Amboy Crater is a volcanic cinder cone that has a day use area with picnic tables, vault toilets, and a viewing awning. Three hours is recommended for the hike to the crater, I did it in a little less but did not spend long since it was getting dark. I forgot to take my camera so all the pictures are from near the parking area. The bottom of the cone is just some cracked mud, with slopes of black and red volcanic rocks in every direction.
Since I was the only person there, I don't feel guilty about spending the night in the main lot rather than moving to the small paved overflow lot. The train tracks aren't particularly close, but the frequent trains can be heard quite well. Verizon internet connection was slow but usable.