Natural acidity and hundreds of years of mining have created this canvas - the famous 'painted river', the Rio Tinto, in Andalusia, Spain. Mineral ores (especially iron ore) oxidize when they come into contact with the air, staining the water and the land shades of red, orange and brown. Francisco has devoted more than 25 years to photographing the river, walking its length, diving in it, flying over it and exploring the mines. He took this aerial image of its copper-tinted waters from 500 metres (1640 feet) above the ground. It's a sight that he considers to be the perfect fusion of art and nature. 'I had to measure light, adjust the camera settings and compose images in fractions of a second, all the while fighting nausea and clinging to my camera in the strong wind.' The extraterrestrial impression may not be just artistic licence: astrobiologists think that the bacteria here live in conditions similar to those found on Mars.