Grand Prismatic Overlook Trail

From the Fairy Falls parking lot, you'll follow a flat, wide former road bed before the trail splits off and begins a gentle climb through lodgepole pine forest. Gentle is the operative word here — the elevation gain is roughly equivalent to walking up a ten-story building, spread over enough distance that most people barely notice. The trees thin out as you ascend a hillside, and then the boardwalk-style overlook platform appears, and suddenly you're staring down at the largest hot spring in North America — a massive, alien eye of deep blue ringed with bands of orange, yellow, and green that look Photoshopped but are actually thermophilic bacteria doing their thing. Unlike the boardwalk at Midway Geyser Basin where you're at eye level with the steam, this vantage point lets you actually see the full color spectrum. Every single person with working legs visiting Yellowstone should do this trail.