Doublet Pool, Hot spring in Yellowstone National Park, US.

Doublet Pool is a hot spring in the Upper Geyser Basin featuring two distinct lobed sections side by side. The water reaches temperatures around 91 degrees Celsius (194.4°F) and is rimmed with pale mineral deposits.

Doublet Pool formed over thousands of years through underground volcanic activity and constant deposits of hot mineral-rich water. These processes created the pool's distinctive two-lobed shape and thermal characteristics.

The name refers to the twin-lobed shape of the pool, which is shaped by mineral buildup. Visitors can observe how the striking colors and surface textures reflect the ongoing thermal activity.

Access is via wooden boardwalks that provide safe viewing while protecting the fragile surroundings. The ground around the pool is hot and unstable, so staying on marked paths is essential for safety.

Only two or three eruptions of Doublet Pool have ever been observed, each lasting no more than 8 minutes. The right-hand pool pulses over its vents roughly every two hours, so timing a visit around that cycle is the best chance to see movement.