Bunsen Peak el. 8,527 feet (2,599 m) is a prominent peak due south of Mammoth Hot Springs in Yellowstone National Park, Wyoming. The peak lies on the east flank of Kingman Pass on the Mammoth to Norris section of the Grand Loop Road. The peak was first ascended by Ferdinand V. Hayden and Captain John W. Barlow in 1871, Bunsen Peak was not named until 1872 during the second Hayden Geologic Survey. E. S. Topping named the peak Observation Mountain in 1872 as well, but that name did not stick. The Bunsen Peak Trail with its trailhead just south of Mammoth is a steep 2.1 miles (3.4 km) to the summit.