The main attraction in the area is the Craters of the Moon National Monument. This huge area of lava flows was formed over a 15000 year period with regular eruptions approximately every 2000 years, which has resulted in the lava fields as they exist today.
It has been described as the weirdest landscape in America. It is certainly a wild and scenic area with plenty of hiking trails, caves and lava formations of various types.
It is like no other national park you will see in the United States. Its geology and history make it a must see.