 Craters of the Moon National Monument and Preserve is a U.S. National Monument and national preserve in the Snake River Plain in central Idaho . It is along US 20 ( concurrent with US 93 and US 26 ) , between the small towns of Arco and Carey , at an average elevation of 5 @,@ 900 feet ( 1 @,@ 800 m ) above sea level . The protected area 's features are volcanic and represent one of the best @-@ preserved flood basalt areas in the continental United States . 
