Castle Geyser erupting.
Castle Geyser.
Upper Geyser Basin in Yellowstone National Park.
Multi-use trail in Upper Geyser Basin.
Wildflowers and brightly colored pools.
Firehole River in Upper Geyser Basin.
The Upper Geyser Basin.
The Upper Geyser Basin.
Firehole River.
Morning Glory Pool.
Upper Geyser Basin.
Thermal spring in Upper Geyser Basin.
Daisy Geyser erupting.
Upper Geyser Basin multi-use trail.
Giant Geyser.
Upper Geyser Basin.
Twin springs in Upper Geyser Basin.
Lion Geyser with Heart Spring in the foreground.
Lion Geyser and Heart Spring.
Thermal streams flowing into the Firehole River.