Aracar is a large conical stratovolcano in northwestern Argentina, just east of the Chilean border. It has a main summit crater about 1–1.5 kilometres (0.6–0.9 mi) in diameter which sometimes contains crater lakes, and a secondary crater. The volcano has formed, starting during the Pliocene, on top of a lava platform and an older basement. Constructed on a base with an altitude of 4,100 metres (13,500 ft), it covers a surface area of 192.4 square kilometres (74.3 sq mi) and has a volume of 148 cubic kilometres (36 cu mi). The only observed volcanic activity was a possible steam or ash plume on March 28, 1993, seen from the village of Tolar Grande about 50 km (31 mi) southeast of the volcano, but with no evidence of deformation of the volcano from satellite observations. Inca archeological sites are found on the volcano.

Ojos de Mar is a group of 3–6 small water bodies close to the town of Tolar Grande in Argentina and an important tourist attraction there. They are inhabited by extremophile microorganisms of interest to biotechnology; stromatolites have also been found there.