What's green, yellow, orange, and brown? The colors of Chromatic Pool, of course! The Chromatic Pool is situated west of the equally colorful but more oversized Beauty Pool. Both sights are beside the trail and are easily viewed close-ups. The greenish-blue pool of Chromatic Spring is about 30 feet in diameter though the vent is much narrower; most are shallow, colored, rich shades of red and orange by cyanobacteria, the deep colors indicating that the water temperature is relatively low. The run-off channel is similarly colored, heading north then bending west and meeting the Firehole River. The spring does not erupt though its water level gradually rises and falls over a long period (weeks to months). Make sure you don't miss the Chromatic Pool and its neighbor, the Beauty Pool - their colors are marvelous!