Among all the geothermal wonders of Yellowstone National Park, none capture the imagination quite like the Grand Prismatic Spring. Located in the Midway Geyser Basin, this massive hot spring is the largest in the United States and the third largest in the world. Its vibrant colors—deep blue center fading to rings of green, yellow, orange, and red—make it look like a living rainbow set into the Earth.

Why Is Grand Prismatic So Colorful?

The striking hues of the spring come from thermophiles—heat-loving microorganisms that thrive in Yellowstone’s hydrothermal waters.

• Center (deep blue): The hottest part of the spring, where almost no microbes survive. The intense heat gives the water its rich blue color.
• Green & Yellow Rings: As temperatures decrease, photosynthetic microbes flourish, adding shades of green and yellow.
• Outer Rim (orange & red): Cooler water supports different bacterial mats that paint the spring’s edge with fiery tones.

Together, these microbial communities create the kaleidoscope effect that has made Grand Prismatic world-famous.

Size & Scale

• Width: About 370 feet (larger than a football field!)
• Depth: 121 feet
• Temperature: Around 160°F (70°C) at the center
• Flow: Over 500 gallons of water per minute

Standing at ground level, the spring feels massive. But its full beauty is best appreciated from above, where the rainbow-like rings can be seen in their entirety.

Best Viewing Spots

• Boardwalks: The Midway Geyser Basin boardwalks bring you right to the edge of Grand Prismatic, letting you feel the steam rising from its surface.
• Fairy Falls Trail Overlook: A short hike (about 1.6 miles round trip) gives the most famous aerial view of the spring, perfect for photography.
• Morning Visits: Cooler air creates more steam, which can partially obscure the colors. Midday, when the sun is high, offers the clearest view.

Things to Do Nearby

The Midway Geyser Basin is packed with other geothermal highlights:

• Excelsior Geyser Crater: Once one of Yellowstone’s most powerful geysers, now a massive steaming pool pouring thousands of gallons of water into the Firehole River.
• Turquoise Pool & Opal Pool: Smaller hot springs with dazzling colors.
• Fairy Falls: A beautiful 200-foot waterfall just beyond the overlook trail.

Tips for Visiting Grand Prismatic Spring

• Stay on Boardwalks: The ground around hot springs is fragile and dangerous.
• Bring a Camera Lens Cloth: Steam can fog your lens quickly.
• Avoid Peak Crowds: Early morning or later afternoon offers more space and quieter moments.
• Wear Layers: Yellowstone weather shifts rapidly, even in summer.
• Parking: The Midway Geyser Basin lot is small and fills up fast—arrive early.

Quick Facts

• Location: Midway Geyser Basin, Yellowstone National Park, Wyoming
• Ranking: Largest hot spring in the U.S., third largest in the world
• Dimensions: 370 feet wide, 121 feet deep
• Colors: Caused by heat-loving bacteria and minerals

Why Grand Prismatic Should Be on Your Yellowstone Itinerary

Grand Prismatic Spring is more than just a hot spring—it’s a natural masterpiece. The surreal colors, immense scale, and steaming landscape make it one of the most breathtaking sights in Yellowstone. Whether you see it from the boardwalk or hike to the overlook, it’s an experience that stays with you long after your trip.

Grand Prismatic is Yellowstone’s rainbow jewel, a must-see for any visitor.                                                                                                                                                                                                                                                                                                                                                                                                 Visit the Ultimate Outdoor Adventure Mega Hub