The photo shows
West Pyrite Pool, one of the largest hot springs in the
Bumpass Hell geothermal basin, Lassen Volcanic National Park. The acidic, greyish water drains via several run-off channels across the colorful earth, combining with the discharge from other pools to form Bumpass Creek, which flows southwards out of the basin. The steaming vent to the right is
Big Boiler, a very active fumarole