Waterfall from Slate Cavern Tunnel entrance, Dinorwig Quarry (Dinorwic Quarry), Eryri (Snowdonia National Park), North Wales, United Kingdom

Young brown bears (Ursus arctos) foraging for salmon at the Brooks River, Katmai National Park, Alaska, United States of America

Adult brown bears (Ursus arctos) foraging for salmon at the Brooks River, Katmai National Park, Alaska, United States of America

Young brown bear (Ursus arctos) foraging for salmon at the Brooks River, Katmai National Park, Alaska, United States of America

Flusstauchen in der Verzasca, Scubadiving in a fre, Scubadiving in a freshwater river

Canoes at Wekiwa Springs near Orlando produces freshwater from the Florida Aquifer, Florida, USA

R?o Tinto, Andalucia, Spain *** Local Caption *** R?o Tinto ("Red River") is very acidic (Ph 2) and has a deep reddish hue due to iron dissolved in water. The acidity of the watercourse is linked to the drainage of pyrite, which is very present in the subsoil. Extremophilic and endemic bacteria and algae colonize the river bed, forming a fragile biofilm that evokes the hot springs of Yellowstone Park in the USA.

R?o Tinto, Andalucia, Spain *** Local Caption *** R?o Tinto ("Red River") is very acidic (Ph 2) and has a deep reddish hue due to iron dissolved in water. The acidity of the watercourse is linked to the drainage of pyrite, which is very present in the subsoil. Extremophilic and endemic bacteria and algae colonize the river bed, forming a fragile biofilm that evokes the hot springs of Yellowstone Park in the USA.

Reflections on Rio Tinto, near its source, Andalusia, Spain *** Local Caption *** R?o Tinto ("Red River") is very acidic (Ph 2) and has a deep reddish hue due to iron dissolved in water. The acidity of the watercourse is linked to the drainage of pyrite, which is very present in the subsoil. Extremophilic and endemic bacteria and algae colonize the river bed, forming a fragile biofilm that evokes the hot springs of Yellowstone Park in the USA.

Waterfalls on the Urederra river in autumn, baquedano Urederra river, Navarra, Spain

Mid-air-mid-water view of the Burles spring, karstic exsurgence of Vauclusian type, on the commune of sainte-Enimie, Lozere, Occitania, France.

Reflection of trees in Tinto river, Rio Tinto minas, Rio Tinto, Huelva, Spain

Waterfalls on the Urederra river in autumn, Navarra, Spain