Black Pool

Black Pool is a world-renowned hot spring located in the West Thumb Geyser Basin of Yellowstone National Park, Wyoming, USA. Historically, the pool earned its name because its relatively cool water allowed dark, thick mats of cyanobacteria and algae to thrive, giving the spring a deep, almost black appearance. However, a significant thermal shift occurred in 1991 when the pool's water temperature rose dramatically due to shifts in geothermal activity. This sudden increase in heat killed off the dark microbes, revealing the pool's true impressive depth and transforming its color into a stunning, crystal-clear, and vibrant shade of blue. Today, despite its misleading historical name, Black Pool is celebrated as one of the most vividly blue and beautiful thermal features in the entire park. Visitors walking along the well-maintained wooden boardwalks of the West Thumb basin can safely marvel at the striking contrast between the intense blue waters and the stunning backdrop of the adjacent Yellowstone Lake. The steam rising from the scalding hot spring creates a mystical atmosphere, making it a spectacular stop for nature lovers.