This is an image of Grand Prismatic Spring at Midway Geyser Basin in Yellowstone National Park. The water is hottest when it enters the spring at the bottom from a crack 121 feet below the surface. The water slowly cools as it comes to the surface, creating a temperature gradient. This temperature gradient is home to different species of bacteria causing the spring to have many different colors. The deepest parts of the spring are a deep blue because the water reflects blue back to those at the surface. Meanwhile, the rest of the spring takes on the color of the bacteria living at that depth of the water.
Photo Credit: Grant Ordelheide
Article: Tori Peglar; Grand Prismatic Spring at Yellowstone’s Midway Geyser Basin