Morning Glory Spring, Yellowstone National Park, United States

The pool was named by Mrs. E. N. McGowan, wife of Assistant Park Superintendent, Charles McGowan in 1883. She called it Convolutus, the Latin name for the morning glory flower of which the springs resemble. By 1889, the name Morning Glory Pool had become common usage in the park. Many early guidebooks called this feature Morning Glory Spring.
Composition
The distinct color of the pool is due to bacteria which inhabit the water. On a few rare occasions the Morning Glory Pool has erupted as a geyser, usually following an earthquake or other nearby seismic activity.