Black Pool Yellowstone National Park

Black Pool is one of the most striking hot springs in Yellowstone National Park, located in the West Thumb Geyser Basin on the shore of Yellowstone Lake. 🔵 Black Pool Overview Location: West Thumb Geyser Basin, southern Yellowstone Type: Hot spring Depth: Estimated over 30 feet deep Color: Deep turquoise blue with black edges (despite the name) Temperature: ~132–142°F (56–61°C) 🖤 Why Is It Called Black Pool? Historically, Black Pool appeared very dark—almost black—because: The water used to be cooler, allowing dark-colored bacteria and microbial mats to grow. These microbes gave it a shadowy, opaque appearance. In 1991, the pool’s temperature increased significantly due to a thermal shift, killing the heat-sensitive organisms and revealing the stunning blue clarity underneath. So ironically, it's no longer black — but the name stuck!

• July Evening Colors