Ключевые слова: background, beautiful, beauty, blue, boardwalk, danger, emerge, environment, forest, fumarole, gas, gases, grass, green, hot spring, lake, landscape, moss, muck, natural, nature, outdoor, park, reflection, river, rock, sky, spring, sulfurous, sulphur, sulphureous, thermal feature, tourism, travel, tree, view, water, wyoming, yellowstone national park,