 The valley is well known as one of the best locations to view wildlife in Yellowstone.The valley was the natural route to Yellowstone Lake as trappers, explorers and natives made their way up the Yellowstone River.On August 29, 1870 when Henry D. Washburn and Gustavus Cheyney Doane ascended Mount Washburn during the Washburn-Langford-Doane Expedition, they saw the great expanse of the Hayden Valley between Yellowstone Falls and the lake.