Emerald Pools vibrant colors are caused by themophilic (heat-loving) cyanobacteria and algae. As the temperature of the pool decreases towards its edges, the colors tend to oranges and yellow. Black Sand Basin.
Location: Black Sand Basin, Yellowstone National Park, Wyoming
Image ID: 07302
Rainbow Pool, a broad (50 foot diam) heated pool in Black Sand Basin, will rarely erupt. Usually it is calm and mildly overflowing, allowing colorful thermophilic cyanobacteria and algae to grow around its edges.
Location: Black Sand Basin, Yellowstone National Park, Wyoming
Image ID: 07303