Rugged volcanic steppe pocked with craters, caves and twisted formations, Pali Aike means 'devil's country' in Tehuelche. This desolate landscape is a 50-sq-km park along the Argentine border. Mineral content made the lava rocks red, yellow or green-gray. Fauna includes abundant guanaco, ñandú, gray fox and armadillo. In the 1930s Junius Bird's excavations at 17m-deep Pali Aike Cave yielded the first artifacts associated with extinct New World fauna such as the milodón and the native horse Onohippidium.
The park has several trails, including a 1.7km path through the rugged lava beds of the Escorial del Diablo to the impressive Crater Morada del Diablo; wear sturdy shoes or your feet could be shredded. There are hundreds of craters, some four stories high. A 9km trail from Cueva Pali Aike to Laguna Ana links a shorter trail to a site on the main road, 5km from the park entrance.