yellowstone sulphur pool with green and yellow wayer on a summer day, with blue sky and clouds and coniferous trees

wilderness mountain lake landscape tree river nature water reservoir reflection valley plateau pond stream cloud park yellowstone sulphur pool green yellow wayer summer day blue sky clouds coniferous trees geothermal thermal caldera hydrothermal hot spring mudpool mud recreation sightseeing attraction vacation travel american famous cauldron acid danger dangerous round earth sinkhole hollow crater national adventure natural forest weather america usa united states popular people