Hayden Valley is a broad subalpine valley in central Yellowstone National Park along the Yellowstone River between Yellowstone Falls and Yellowstone Lake. Its flat, grassy floor is an ancient lake bed from a time when Yellowstone Lake was much larger, and it long served as a natural route for Native people, trappers, and explorers. The valley is generally understood to be named for Ferdinand Vandeveer Hayden, whose 1871 geological survey helped lead to the creation of the park. Known especially for abundant wildlife and scattered geothermal features, it is both a scenic corridor and a protected ecological refuge with limited public access.