Craters of the Moon preserves 618 square miles of lava flows, cinder cones, spatter cones, and lava tube caves across the Snake River Plain — terrain so alien that NASA brought Apollo astronauts here to train for lunar geology before the 1969 moon landing. The most recent eruptions occurred just 2,000 years ago and geologists expect another eruptive episode within the next 1,000 years, making this one of the youngest volcanic landscapes in the contiguous United States.