San Pedro de Atacama grew, over centuries, around an oasis in the Atacama desert. It is located east of Antofagasta, some 100 km (60 mi) southeast of Calama and the Chuquicamata copper mine, overlooking the Licancabur volcano. It features a significant archeological museum, the R. P. Gustavo Le Paige Archaeological Museum, with a large collection of relics and artifacts from the region. Native ruins nearby now attract increasing numbers of tourists interested in learning about pre-Colombian cultures. Tourists also visit for other popular activities including sandboarding and stargazing, with the views of the stars from the Atacama unrivalled across the continent.
The town lies at an average altitude of approximately 2,400m (7,900 ft) and visitors often experience mild altitude sickness such as dizziness, lethargy and headaches. The local climate is extremely dry (with little or no rainfall recorded in the town itself) and mild, with daytime temperatures between 25-30 degrees Celsius (77-86°F) in the summer (December to February) and 18-25 degrees Celsius (64-77°F) in the winter (June to August). Nighttime temperatures routinely drop below zero and can reach as low as -10°C (14°F) in the winter.
In the past it was found that the town's water supply was naturally contaminated with high levels of the heavy metal arsenic which leaches from adjacent salt lakes, with levels of as high as 600µg per litre (60 times the WHO recommended maximum) being recorded. Interestingly the indigenous population seem to have developed a natural tolerance to this otherwise toxic metal and suffered few ill effects from drinking the water. Recently a filtration plant has been installed in the town which has reduced the levels of arsenic and other contaminants in the local water supply.