For many years, this vertiginous 1.5 kilometer route through the El Chorro gorge was in a state of poor repair and closed to the public. A number of people who ignored the warnings fell to their death. Fully repaired in 2015, it has proven enormously popular, making it essential to book beforehand via a website or to hire a local guide. The walkway, created a century ago to provide access for workers to the nearby Conde del Guadalhorce dam, and particularly the hanging bridge above a sheer 105-meter drop, are not for the faint hearted.Diputación de MálagaOne of the most popular routes in the Valle de Ordesa, in the foothills of the Spanish Pyrenees, changes as the walker ascends from the deep green meadows of the valley floor, up through beech and pine forests into high pasture areas dotted with log cabins. The glacial cirque at Soaso, dominated by the Cola de Caballo waterfall, marks the end of the 17.5 kilometer route.Guido Cozzi/CorbisKnown locally as the Garganta Divina, or divine throat, this 12-kilometer route takes the visitor through narrow tunnels, and along even narrower pathways that fall away to rocky escarpments along the route of the Cares river, which marks the border between Asturias and León. The route was created more than half a century ago to provide access to the Camarmeña-Poncebos hydro-electric plant.Westend61/AGEThis Y-shaped 22-kilometer trail follows a former miners’ railroad through the Trubia valley, linking the villages of Tuñón, Teverga, and Quirós. At the Casa del Oso, the headquarters of a foundation to protect bears, visitors can hire bicycles and explore the Picos de Europa mountains.Ian Cook/AGEThis recently created five-kilometer route through the arid landscape of the Monasterio de Piedra is lined with caves and waterfalls, the most impressive of which is the 50-meter Cola de caballo. Entrance to the park costs €15.50 (€11 for children and pensioners) and includes a display of birds of prey.Jose Fuste Raga/AGEThe dense forests of Irati can be accessed from Orbaizeta in the west, or via Ochagavía in the east, where there is a visitors’ center. A network of signposted routes of varying difficulty and length, lead the visitor into one of Europe’s largest and best conserved beech forests, on a par with Germany’s Black Forest. In winter, it is possible to explore using skis and snow shoes, and in summer on foot or by bike. Just watch out for the witches and Basajaun, the lord of the forest.Tono Balaguer/AGEThere are several routes open to the public that lead to Fortaleza and Pico Viejo, at some 3,555 meters. The peak of the Teide crater is reached via route number 10, named after Telesforo Bravo, the local geologist who dedicated his life to studying the volcano, and requires a special permit issued by the park authorities via their website. The peak is usually snowbound between November and April.Michael Fischer/AGEThere are around 15 short trails inside Cañón del Río Lobos Natural Park, which sits between the provinces of Soria and Burgos. A dramatic landscape has been created by erosion of the limestone, creating karst caves through which underground rivers flow.José Antonio Moreno/AGEOnce nicknamed “The Mirrors of La Mancha,” the Lagunas de Ruidera Natural Park comprises 16 interconnected lakes fed by vast aquifers that stretch for 20 kilometers through a low valley, and which Cervantes mentions in ‘Don Quixote.’ Like the nearby Tablas de Daimiel, the area attracts huge numbers and varieties of birds.José Antonio Moreno / AGE