This is a colorful blue image of a geothermal spring at West Thumb in Yellowstone National Park. The eye is drawn to the lower third of the frame by the precipitous hole into the abyss. The image also provides a good sense of how thin the ground is at the edge of the pool. The blue color of the spring is caused by thermophiles, heat-loving bacteria, that live in the nearly boiling water. These bacteria are also used by pharmaceutical companies for research and to develop new drugs and treatents. Also, these geothermal pools are a large attration for tourists visiting Yellowstone.