Photo taken on Aug. 10, 2011 shows the scenery of Yellowstone Lake at dusk in Yellowstone National Park, the United States. Established in 1872, Yellowstone is a national park located primarily in the state of Wyoming, although it also extends into Montana and Idaho. Yellowstone was the first national park in the world and is known for its wildlife and its many geothermal features. [Xinhua/Shen Hong]