 Craters of the Moon is in south @-@ central Idaho , midway between Boise and Yellowstone National Park . The lava field reaches southeastward from the Pioneer Mountains . Combined U.S. Highway 20 – 26 – 93 cuts through the northwestern part of the monument and provides access to it . However , the rugged landscape of the monument itself remains remote and undeveloped , with only one paved road across the northern end . 
