Wikimedi'Òc

Sizzling Basin and Churning Caldron in Yellowstone National Park, Wyoming, US.jpg - Semiautonomous

Mud Geyser in Yellowstone National Park, Wyoming, US.jpg - Semiautonomous

Black Dragon's Caldron and Sour Lake in Yellowstone National Park, Wyoming, US.jpg - Semiautonomous

Mud Caldron in Yellowstone National Park, Wyoming, US.jpg - Semiautonomous

Turbulent Pool in Yellowstone National Park, Wyoming, US.jpg - Semiautonomous