Horseback riding is easy to set up and follows beautiful routes through the Cordillera Negra [1].
A recommended outfit in Yungay [2], a village 20 minutes north of Huaraz [3], is La Posada de Yungay (Km 219 Huaraz-Caraz Highway, tel. 043/978-4732, edergirald [at] hotmail [dot] com, US$8 per hour). Guide Eder Giraldo offers excellent day trips in the Cordillera Negra, as well as longer rides into the Cordillera Blanca [4]’s Quebrada Ishinca.
Links:
[1] http://www.moon.com/destinations/peru/huaraz-and-the-cordillera-blanca/trekking-the-andes/cordillera-negra
[2] http://www.moon.com/destinations/peru/huaraz-and-the-cordillera-blanca/callejon-de-huaylas/yungay
[3] http://www.moon.com/destinations/peru/huaraz-and-the-cordillera-blanca/huaraz
[4] http://www.moon.com/destinations/peru/huaraz-and-the-cordillera-blanca/trekking-the-andes/cordillera-blanca