The Río San Guillermo flows through one of Argentina's most remote and pristine high-Andean landscapes, winding through the San Guillermo Biosphere Reserve and National Park in the Iglesia Department of San Juan Province. Set against a dramatic backdrop of towering peaks reaching elevations between 2,100 meters (6,900 ft) and 6,380 meters (20,930 ft), this river carves through barren desert terrain, puna grasslands, and scattered high-altitude wetlands in the arid Andes. The surrounding wilderness is home to vicuña, guanaco, culpeo fox, Andean mountain cat, cougar, and Andean condor, making any fishing expedition here as much a wildlife experience as an angling one. The nearest town of note is Rodeo, located in San Juan Province, which serves as a gateway to this extraordinarily wild and seldom-visited region.