Hike up to (almost) the summit of Caballo Mountain, the tallest peak in Los Alamos county (you cannot quite reach the summit, as it lies within the Santa Clara Indian Reservation). The climb to the top gives an amazing view of the Rio Grande gorge out to the Sangre de Cristo mountains. The hike can be challenging, as it goes in and out of Guaje Canyon, but will you give you even more terrain to enjoy. The trailhead starts at the Pajarito Mountain Ski Area, so there should be no parking fee, although winter time may change this. The trail is popular with mountain bikes & trail runners as well. During the winter, the beginning of this trail falls within the Southwest Nordic Ski Club's groomed cross-country ski trails and snowshoeing trails.