Emerald Spring was named for its emerald color. The color is due to the refraction of blue by the water combined with yellow from sulfur deposits lining the pools walls. Emerald is usually many degrees below boiling. Bubbles seen rising to the surface are due to steam, carbon dioxide and other gasses. This is not always true though. At times, especially at times of a disturbance, Emerald Spring can become turbid and begin to boil and sometimes even erupt to 3 feet or so. In 1931, Emerald saw spectacular activity. It was in eruption fully 87% of the time with some bursts reaching 60 to 75 feet.
The 36 feet wide, 30 to 40 feet long pool is about 155 degrees Fahrenheit.