spring in yellowstone: indigo spring of the excelsior group in midway geyser basin with firehole river and midway bluff behind

background basin bluff caldera clouds day environment excelsior feature firehole forest geology geothermal geyser group hill hillside horizon hot hydrothermal indigo landscape late midw midway national natural nature nps outdoor panorama park pool river scenery scenic sky spring steam thermal tourism travel trees vapor view volcano water white wyoming yellowstone