Sapphire Pool, Biscuit Basin, Upper Geyser Basin, Yellowstone National Park, UNESCO World Heritage Site, Wyoming, United States of America, North America

Pines at Mystic Falls, near Biscuit Basin, Yellowstone National Park, UNESCO World Heritage Site, Wyoming, United States of America, North America

Geothermal mud pot in Biscuit Basin in Yellowstone National Park, UNESCO World Heritage Site, Wyoming, United States of America, North America

Turquoise clear water of a hot spring, Sapphire Pool, Black Sand Basin and Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Yellow bacteria and algae in a hot spring at Black Sand Basin and Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Tourist on a logging road in front of steaming hot spring, Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Black Opal Pool, Hot Spring, Yellow Algae and Mineral Deposits, Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Turquoise clear water of a hot spring, Sapphire Pool, Black Sand Basin and Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Shell Spring, geyser, hot spring, Biscuit Basin, Yellowstone National Park, Wyoming, USA

Aerial photograph, University of Essen-Duisburg, biscuit tins, Duisburg, Ruhr Area, North Rhine-Westphalia, Germany, Europe

Aerial photo, Essen University, the Gerhard Mercator University, "biscuit tins", Duisburg, Ruhr area, North Rhine-Westphalia, Germany, Europe

Black Opal Spring, geyser, Biscuit Basin, Upper Geyser Basin, Yellowstone National Park, Wyoming, United States of America, USA

Mustard Spring, geyser, Biscuit Basin, Upper Geyser Basin, Yellowstone National Park, Wyoming, United States of America, USA

Avoca Spring, Yellowstone National Park, Wyoming, USA, North America

Sapphire Pool, Yellowstone National Park, Wyoming, USA, North America

Elks and geyser, Biscuit Basin, Yellowstone national park, Wyoming, USA / (Cervus canadensis)

Sapphire Pool, geyser, Biscuit Basin, Upper Geyser Basin, Yellowstone National Park, Wyoming, United States of America, USA

Drainage area of the Sapphire Pool, geyser, coloured thermophilic bacteria, microorganisms, Biscuit Basin, Upper Geyser Basin, Yellowstone National Park, Wyoming, United States of America, USA

Creek and pool in Biscuit Basin, Yellowstone National Park, Wyoming.

Sapphire Pool in Biscuit Basin, Yellowstone National Park, Wyoming.

Black Opal Pool in Biscuit Basin, Yellowstone National Park, Wyoming.

Sapphire Pool in Biscuit Basin, Yellowstone National Park, Wyoming.