The Termas de Colina sit at 2,500 meters elevation, where geothermal runoff from the Volcán San José creates a cascade of seven stone-rimmed pools descending a natural ravine. The thermal water emerges at 52°C and cools as it spills downward, offering bathers a choice of temperatures ranging from scalding upper basins to temperate lower terraces. The site opened to visitors in the 1970s when a dirt access road was cut through the Cajón del Maipo, though local herders had used the springs for decades prior. Today the facility remains deliberately minimal—stone walls, gravel paths, a single changing shed—preserving the raw mountain context that defines the experience. The springs function as the anchor point for day trips that combine multiple Andean landmarks within a single circuit. Most termas de colina tour packages pair the thermal pools with a stop at Embalse del Yeso, the turquoise reservoir sixteen kilometers southeast, where meltwater from San José accumulates behind a 1964 earth-fill dam. The reservoir sits in a glacial valley flanked by vertical rock faces, its color shifting from jade to cobalt depending on sediment load and sun angle. Some itineraries add intermediate stops at the Chocolate House in San Alfonso or viewpoint pauses along the Maipo River canyon, extending total tour duration to nine or ten hours round-trip from Santiago. The thermal water's mineral content—sulfate, calcium, magnesium—derives from subsurface interaction with volcanic bedrock. Regular soakers claim therapeutic benefit for joint pain and circulation, though no formal studies document the springs' medical efficacy. The site's appeal rests less on wellness claims than on the conjunction of heat and altitude: immersing in 40°C water while snow patches cling to the ridgeline above creates a sensory dissonance that photographs fail to convey. Access remains open year-round at the standard 8,000 CLP entrance fee, though winter months bring road closures when snowfall blocks the unpaved final approach. The springs see heaviest traffic on weekends between November and March, when Santiago residents flee urban heat for mountain cold and paradoxically seek warmth in heated pools. Operators running Cajón del Maipo hot springs excursions typically schedule early departures to secure parking before midday crowds arrive, then structure the day to visit Yeso during optimal midmorning light.