Barely an hour southeast of downtown Santiago , the Río Maipo has cut a deep canyon through more than 70 kilometers of the Andean foothills before it meanders onto the plains near the town of Pirque. Once the border of the Kollasuyu, the Inka empire’s southernmost limits, the Cajón del Maipo (Canyon of the Maipo) is one of urban Santiago’s great escapes, barely an hour from the Plaza de Armas .
Starting with fine wineries at Pirque  and Santa Rita , the canyon just gets better as it climbs toward the Andean crest. While parts of the main road are cluttered with cabañas, campgrounds, and restaurants, it still provides access to plenty of high and wild country—not to mention the river itself. Paved as far as Romeral, it and a parallel road from Pirque are good enough for touring bikes, but other routes are suitable for mountain bikers, and hikers and horseback riders can explore the trails of Monumento Natural El Morado  and the private nature reserve Cascada de las Ánimas .
The Class III–IV Río Maipo provides plenty of thrills for rafters and kayakers even though diversions for irrigation works and even more from sand and gravel quarrying have taken their toll. At the end of the day, rustic hot springs are suitable for a soak. While the area gets crowded in summer and on weekends and holidays, especially from December to March, the rest of the year it’s pretty sedate.
Transportation to the Cajón del Maipo is good and getting better. From the new Puente Alto Metro station, Buses Cajón del Maipo (tel. 02/8611518) ascends as far as San José de Maipo  every eight minutes, to San Alfonso  (US$1.40) every half hour, and to San Gabriel (US$2.30) hourly. From the Bellavista de La Florida station, it also goes to Baños Morales (US$7.50 round-trip) Saturday and Sunday at 8:30 a.m. all year; in summer, departures are daily. Taxi colectivos also shuttle up and down the canyon from the Puente Alto Metro.