Craters of the Moon National Monument, ID. After brief walks around some cinder cones and other vulcanism, Peggy, Max, Samantha, and I walked out to the Dew Drop and Indian Tunnel caves. This was on a paved trail across the lava fields. It was hot in the sun however once we got 20 ft. underground, it was rather cool and water was dripping. The Dew Drop lava tube cave was roomy but only a bit larger than house sized. The second, Indian Tunnel, was well over 100m long with some parts of the roof caved-in. It must have been 30ft. deep or more. It was well worth the hike! We ended up the day with riding across a flat desert (the result of past Yellowstone-like caldera--hot spots 10s of millions of years ago) seeing distant volcanos, and staying in Idaho Falls, ID.