Massive, and a complete contrast to Valentine: where that one still looks like the day the lava cooled, this is mostly breakdown, meaning the original ceiling came down and the boulders are what you are walking over. The trail through it was built by the CCC. Take the long stairways right down to the chilly bottom and there is a year-round ice floor to look at, which on a hot Modoc Plateau afternoon is worth the descent on its own.
Other places on the map within a couple of hours.
