The beauty and magnificence of most national and natural parks is best appreciated on the earth's surface. Impressive mountains, craggy landscapes, wetlands and rolling hills. Not so the Karst en Yesos de Sorbas Nature Reserve in eastern Andalucía, at the far east of the Tabernas-Sorbas sub-desert corridor, the most arid region in Europe.
Sure, there are walks through some spectacular and unique gypsum landscapes where you will see plants exclusive and endemic to this region and animal species emblematic to the reserve, the spur thighed tortoise, eagle owls and Bonelli's eagle. But there are clues that much remains hidden beneath your feet. Sinkholes, often marked by a fig tree, dot the landscape, and springs, such as Los Molinos, well up in the Rio Aquas canyon. The Karst formations act as a huge sponge, collecting and storing all the rainwater, which then comes out through these springs.
Beneath your feet there are more than 1,000 caves, most of which are interconnected, and a spectacular, varied array of crystalline formations: stalactites, stalagmites, columns and cave corrals. Rainwater slowly dissolves the gypsum rock, giving rise to an abundance of closed depressions, or sinkholes, on the surface. This is where the karst "windows" appear, the sink-holes and caves connect the arid surface with the complex network of galleries underground. Water penetrates through these windows and continues its erosive, smoothing action, creating Spain's largest subterranean cave system and the world's second largest (yet discovered) in gypsum: the Cueva del Agua system, which is almost 8,500 metres long.