Things to Do at Grand Prismatic Spring

Grand Prismatic Spring is genuinely one of those natural wonders that manages to exceed even the most hyped expectations. At about 370 feet across, it's the largest hot spring in the United States and third-largest in the world, but honestly, the size isn't what stops you in your tracks - it's the absolutely surreal rainbow of colors radiating from deep blue at the center to brilliant oranges and yellows at the edges. The whole thing looks like someone spilled a painter's palette across the landscape. What you're actually seeing is a complex ecosystem at work. The center stays around 189°F, too hot for most life, which keeps it that deep blue color. As the water spreads outward and cools, different heat-loving bacteria create those vivrant rings of color - yellows, oranges, and reds that shift with the seasons and water temperature. It's the kind of place that makes you understand why early explorers' reports were dismissed as tall tales.

Grand Prismatic sits in the Midway Geyser Basin, roughly halfway between Madison and Old Faithful along the Grand Loop Road. From the west entrance, it is ~7 miles south-you'll spot those massive steam plumes long before you reach the parking area. Easy to find. The boardwalk starts right from the parking lot, though that lot fills up fast in summer, sometimes by 9am. There's overflow parking about a quarter-mile away, and the short walk won't kill you. Just plan accordingly.