What makes Craters of the Moon so special geologically?

Craters of the Moon is literally an outdoor classroom to study volcanic geology. The Craters of the Moon lava field is the largest basaltic, dominantly Holocene (last 10,000 years) lava field in the lower 48 states. It has nearly every type of feature associated basaltic systems and park trails give convenient access to most of them. So short of going to Alaska or Hawaii, this is one of the best places in the United States to study this type of volcanism.