Chromatic Pool

Chromatic Pool, one of the stunning thermal wonders of Yellowstone’s Upper Geyser Basin, is a mesmerizing hot spring that lives up to its colorful name. This large, vividly hued pool captivates visitors with shades of blue, green, orange, and yellow that seem to shift with the seasons and the water temperature. Located near Beauty Pool and not far from the world-famous Old Faithful, Chromatic Pool is an example of Yellowstone’s geothermal artistry—where heat, minerals, and microorganisms blend to create a living canvas of natural color.

Chromatic Pool

Quick Reference: Chromatic Pool

Feature	Details
Name	Chromatic Pool
Location	Upper Geyser Basin, Yellowstone National Park, Wyoming, USA
Type	Hot Spring
Nearby Feature	Beauty Pool (hydrologically connected)
Average Temperature	133.1°F (56.2°C)
Average pH	8.5 (slightly alkaline)
Average Conductivity	2096 µS/cm
Colors Origin	Thermophilic bacteria and algae reacting to temperature gradients
Water Activity	No eruptions; gentle bubbling and steam release
Formation	Heated groundwater circulates through mineral-rich rock, dissolving and depositing silica at the surface
Unique Behavior	Shares an underground system with Beauty Pool — as one rises, the other lowers
Visual Highlights	Blue center surrounded by green, yellow, and orange microbial mats
Accessibility	Easily viewed from the Upper Geyser Basin boardwalk
Best Viewing Time	Morning or late afternoon for vivid color contrast and steam visibility
Safety Note	Stay on boardwalks; surface crust is thin and unstable
Fun Fact	Its name “Chromatic” comes from its vivid, ever-changing color palette caused by heat-loving organisms

The pool’s name, “Chromatic,” perfectly describes its ever-changing appearance. Its deep center typically glows a rich sapphire blue, surrounded by rings of lighter blue, green, and yellow, before blending into orange and brown at the edges. These colors are produced by thermophilic microorganisms—heat-loving bacteria and algae—that thrive at different temperature ranges. When the water cools, the outer edges of the pool become home to more colorful microbial mats, painting the spring with intense hues that photographers and visitors find irresistible.

Chromatic Pool is closely related to its neighboring Beauty Pool, and the two share a fascinating geothermal connection. The pair operates like communicating vessels—when the water level in Chromatic Pool rises, the water level in Beauty Pool tends to drop, and vice versa. This phenomenon occurs because they share an underground plumbing system that shifts geothermal energy back and forth between the two springs. As a result, both springs periodically experience changes in color intensity and water clarity. Beauty Pool typically displays its most vibrant hues when it is hottest, while Chromatic Pool often becomes deeper and bluer during cooler phases.

The scientific measurements of Chromatic Pool offer a glimpse into its thermal character. The pool has an average temperature of 133.1°F (56.2°C), which is cooler than many nearby geysers but still hot enough to prevent most forms of life other than specialized thermophiles. It maintains an average pH of 8.5, indicating slightly alkaline water, and an average conductivity of 2096 µS/cm, a sign of its rich mineral content. Silica, sulfur, and other dissolved minerals contribute to the bright sinter crust that lines the pool’s edges, giving it a shimmering, almost metallic appearance under sunlight.

Visitors can easily view Chromatic Pool along the boardwalk system in the Upper Geyser Basin, not far from the Biscuit Basin area. It’s a quieter, less-crowded spot compared to Old Faithful, making it ideal for those who want to experience Yellowstone’s geothermal beauty in a more serene setting. The best time to visit is in the early morning or late afternoon, when steam hangs over the pool and sunlight enhances its kaleidoscope of colors.