Fiery Furnace gets its name from the reddish orange colour of its chimneys and sandstone towers, which resemble flames at dusk. However, the passages are so narrow and shaded that it tends to be one of the less hot places in the Arches National Park. A ranger-guided tour is fascinating and strongly recommended, especially for first-timers here, as navigating this complex labyrinth between towering walls is no mean feat.