Water from these mountains ends up in the taps of Cartagena. The Taibilla river, which rises in the hills above Nerpio, feeds the canals of the Mancomunidad de los Canales del Taibilla, built in the twentieth century to supply towns across Murcia and beyond, and a name like the engineers' houses hints at how much that project marked the valley. Las Casas de los Ingenieros II is a rock shelter near Nerpio, one of the many painted sites in this remote corner of the Sierra de Segura.
The valley around Nerpio is a green oasis in dry mountains. Walnut trees line the river terraces, and the village is known for its nuts, sold in sacks in autumn. The surrounding ridges are covered with pine and juniper, cliffs rise above the valley, and the sky is huge. Letur, to the north, is a village with a Moorish layout of narrow alleys, arches and streams running through the streets, and Yeste, to the northwest, has a castle and a big reservoir nearby.
The roads in this area are long, winding and challenging, with many tight bends, steep climbs and descents, and changing surfaces. Traffic is minimal, and you can ride for an hour without meeting another vehicle. The route east toward Moratalla crosses high, wild country, and the road north toward Yeste and Letur follows valleys and ridges. Rockfall and gravel are common, and in winter snow and ice can close higher roads.
Fuel is scarce. the village has a bar or two but little else for a traveller, and Moratalla, the nearest town of size, is over thirty kilometres away. Yeste, about twenty kilometres away, is bigger than Nerpio. Fill up before entering the sierra and carry water and food. In Nerpio and Yeste, bars and restaurants serve mountain food, lamb, game, stews and cured meats, and the local walnuts appear in desserts.