Castle Geyser in eruption at Yellowstone National Park, Wyoming.

Looking at lava flow at Craters of the Moon National Monument, Idaho.

Looking at volcanic bombs at Craters of the Moon National Monument, Idaho.

Water hole at Craters of the Moon National Monument, Idaho.

Entrance to a cave at Craters of the Moon National Monument, Idaho.

Exploring a cave at Craters of the Moon National Monument, Idaho.

Snake River Canyon, Idaho.

Lower Falls of the Yellowstone River, Wyoming.

Water hole marker at Craters of the Moon National Monument, Idaho.

Lava flows at Craters of the Moon National Monument, Idaho.

Canyon below Shoshone Dam, Wyoming.

Shoshone Dam near the entrance to Yellowstone Park, Wyoming.