Sunlight gives the spring its vivid colors. The brilliant blue of the water is caused by sunlight being scattered by mineral particles in the water, and the spring often appears to have a blue haze hovering over it because the steam reflects the blue from the water. Bright orange heat-loving bacteria known as thermophiles populate the run-channels. These microbes contain colorful pigments that allow them to make energy from sunlight and thrive in the hot conditions of the spring.

Photo: Barry Swackhamer

Photo: Barry Swackhamer

Mammoth, Wyoming · USA